Measuring system having a measuring transducer of vibration-type

ABSTRACT

The measuring system comprises: A measuring transducer of vibration-type, through which medium flows during operation and which produces primary signals corresponding to parameters of the flowing medium; as well as a transmitter electronics electrically coupled with the measuring transducer for activating the measuring transducer and for evaluating primary signals delivered by the measuring transducer. The measuring transducer includes: At least one measuring tube for conveying flowing medium; at least one electro-mechanical, oscillation exciter for exciting and/or maintaining vibrations of the at least one measuring tube; as well as at least a first oscillation sensor for registering vibrations at least of the at least one measuring tube and for producing a first primary signal of the measuring transducer representing vibrations at least of the at least one measuring tube. The transmitter electronics, in turn, delivers at least one driver signal for the exciter mechanism for effecting vibrations of the at least one measuring tube and generates, by means of the first primary signal, as well as with application of a damping, measured value, which represents an excitation power required for maintaining vibrations of the at least one measuring tube, and, respectively, a damping of vibrations of the at least one measuring tube as a result of inner friction in the medium flowing in the measuring transducer, a pressure difference, measured value, which represents a pressure difference occurring between two predetermined reference points in the flowing medium.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Nonprovisional which claims the benefit of U.S.Provisional Application No. 61/291,653 filed on Dec. 31, 2009.

FIELD OF THE INVENTION

The invention relates to a measuring system for flowable, especiallyfluid, media, especially a measuring system embodied as a compact,measuring device and/or as a Coriolis mass flow measuring device,wherein the measuring system comprises: A measuring transducer ofvibration-type, through which medium flows during operation at least attimes and which generates primary signals influenced by at least onemeasured variable, especially a mass flow, a density, a viscosity, etc.,characterizing the flowing medium; as well as a transmitter electronicselectrically coupled with the measuring transducer and processing intomeasured values primary signals delivered by the measuring transducer.

BACKGROUND OF THE INVENTION

In industrial measurements technology, especially also in connectionwith the control and monitoring of automated manufacturing processes,for ascertaining characteristic measured variables of media, forexample, liquids and/or gases, flowing in a process line, for example, apipeline, often such measuring systems are used, which, by means of ameasuring transducer of vibration-type and a transmitter electronicsconnected thereto and most often accommodated in a separate, electronicshousing, induce reaction forces in the flowing medium, for example,Coriolis forces, and produce, repetitively derived from these,measurement values correspondingly representing the at least onemeasured variable, for example, a mass flow rate, a density, a viscosityor some other process parameter. Such measuring systems—often formed bymeans of an In-line measuring device in compact construction withintegrated measuring transducer, such as, for instance, a Coriolis massflow meter,—are long since known and have proven themselves inindustrial use. Examples of such measuring systems having a measuringtransducer of vibration-type or also individual components thereof, aredescribed e.g. in EP-A 317 340, JP-A 8-136311, JP-A 9-015015, US-A2007/0113678, US-A 2007/0119264, US-A 2007/0119265, US-A 2007/0151370,US-A 2007/0151371, US-A 2007/0186685, US-A 2008/0034893, US-A2008/0141789, U.S. Pat. Nos. 4,680,974, 4,738,144, 4,777,833, 4,801,897,4,823,614, 4,879,911, 5,009,109, 5,024,104, 5,050,439, 5,291,792,5,359,881, 5,398,554, 5,476,013, 5,531,126, 5,576,500, 5,602,345,5,691,485, 5,734,112, 5,796,010, 5,796,011, 5,796,012, 5,804,741,5,861,561, 5,869,770, 5,926,096, 5,945,609, 5,979,246, 6,047,457,6,092,429, 6,073,495, 6,311,136, 6,223,605, 6,330,832, 6,397,685,6,513,393, 6,557,422, 6,651,513, 6,666,098, 6,691,583, 6,840,109,6,868,740, 6,883,387, 7,017,424, 7,040,179, 7,073,396, 7,077,014,7,080,564, 7,134,348, 7,216,550, 7,299,699, 7,305,892, 7,360,451,7,373,841, 7,392,709, 7,406,878, WO-A 00/14 485, WO-A 01/02 816, WO-A2004/072588, WO-A 2007/040468, WO-A 2008/013545, WO-A 2008/07 7574, WO-A95/29386, WO-A 95/16897 or WO-A 99 40 394. Each of the thereinillustrated measuring transducers comprises at least one, essentiallystraight, or curved, measuring tube accommodated in a measuringtransducer housing and conveying, or guiding, the, in given cases, alsoextremely rapidly, or extremely slowly, flowing, medium. In operation ofthe measuring system, the at least one measuring tube is caused tovibrate for the purpose of generating oscillation forms influenced bythe medium flowing through the measuring tube.

Selected as excited oscillation form—the so-called wanted mode—in thecase of measuring transducers having curved, e.g. U, V- or Ω-likeformed, measuring tubes is usually that eigenoscillation form, in thecase of which the measuring tube moves in a pendulum-like manner atleast partially in a lowest natural resonance frequency about animaginary longitudinal axis of the measuring transducer, like acantilever clamped on one end, whereby Coriolis forces are induced inthe through flowing medium dependent on the mass flow. These forces, inturn, lead to the fact that superimposed on the excited oscillations ofthe wanted mode, in the case of curved measuring tubes, thuspendulum-like, cantilever oscillations, are thereto equal-frequency,bending oscillations according to at least one, likewise natural, secondoscillation form, the so-called Coriolis mode. In the case of measuringtransducers with curved measuring tube, these cantilever oscillations inthe Coriolis mode caused by Coriolis forces usually correspond to thateigenoscillation form, in the case of which the measuring tube alsoexecutes rotary oscillations about an imaginary vertical axis directedperpendicular to the longitudinal axis. In the case of measuringtransducers with straight measuring tube, in contrast, for the purposeof producing of mass flow dependent Coriolis forces, often such a wantedmode is selected, in the case of which the measuring tube executes, atleast partially, bending oscillations essentially in a single imaginaryplane of oscillation, such that the oscillations in the Coriolis modeare bending oscillations of equal oscillation frequency coplanar withthe wanted mode oscillations. Due to the superpositioning of wanted- andCoriolis modes, the oscillations of the vibrating measuring tuberegistered by means of the sensor arrangement on the inlet side and onthe outlet side have a measurable phase difference also dependent on themass flow. Usually, the measuring tubes of such measuring transducers,applied e.g. in Coriolis mass flow meters, are excited during operationto an instantaneous natural resonance frequency of the oscillation formselected for the wanted mode, especially with oscillation amplitudecontrolled to be constant. Since this resonance frequency is dependent,especially, also on the instantaneous density of the medium,supplementally also the density of flowing media can be measured bymeans of market-usual Coriolis mass flow meters, in addition to the massflow. Additionally, it is also possible, as, for example, shown in U.S.Pat. No. 6,651,513 or U.S. Pat. No. 7,080,564, directly to measure, bymeans of measuring transducers of vibration-type, the viscosity of thethrough flowing medium, for example, based on an exciter energy orexcitation power required for maintaining the oscillations, and/or basedon a damping of oscillations (especially those in the aforementionedwanted mode) of the at least one measuring tube resulting from adissipation of oscillatory energy. Moreover, also other measuredvariables derived from the aforementioned primary measured values ofmass flow rate, density and viscosity can be ascertained, such as, forinstance, the Reynolds number; compare U.S. Pat. No. 6,513,393.

In the case of measuring transducers having two measuring tubes, theseare most often integrated into the process line via a flow dividerextending on the inlet side between the measuring tubes and aninlet-side connecting flange as well a via a flow divider extending onthe outlet side between the measuring tubes and an outlet-sideconnecting flange. In the case of measuring transducers having a singlemeasuring tube, the latter communicates with the process line most oftenvia an essentially straight connecting tube piece opening on the inletside, as well as via an essentially straight connecting tube pieceopening on the outlet side. Additionally, each of the illustratedmeasuring transducers having a single measuring tube comprises, in eachcase, at least one one-piece or multipart, for example, tube-, box- orplate-shaped, counteroscillator, which is coupled to the measuring tubeon the inlet side for forming a first coupling zone and which is coupledto the measuring tube on the outlet side for forming a second couplingzone, and which, during operation, essentially rests or oscillatesopposite-equally to the measuring tube, thus with equal frequency andopposite phase. The inner part of the measuring transducer formed bymeans of measuring tube and counteroscillator is most often held,especially in a manner enabling oscillations of the inner part relativeto the measuring tube, in a protective measuring transducer housingalone by means of the two connecting tube pieces, via which themeasuring tube communicates during operation with the process line. Inthe case of the measuring transducers, for example, as illustrated inU.S. Pat. Nos. 5,291,792, 5,796,010, 5,945,609, 7,077,014, US-A2007/0119264, WO-A 01 02 816 or also WO-A 99 40 394, having a single,essentially straight, measuring tube, the latter and thecounteroscillator are, as in the case of conventional measuringtransducers quite usual, oriented essentially coaxially relative to oneanother. In the case of usually marketed measuring transducers of theaforementioned type, most often also the counteroscillator isessentially tubular and embodied as an essentially straight, hollowcylinder, which is so arranged in the measuring transducer, that themeasuring tube is at least partially jacketed by the counteroscillator.Most often used as materials for such counteroscillators, especiallyalso in the case of application of titanium, tantalum or zirconium forthe measuring tube, are comparatively cost effective steel types, suchas, for instance, structural steel or free-machining steel.

For exciting oscillations of the at least one measuring tube, measuringtransducers of vibration-type have, additionally, an exciter mechanismdriven during operation by an electrical driver signal, e.g. acontrolled electrical current, generated and correspondingly conditionedby the mentioned driver electronics. The exciter mechanism excites themeasuring tube to bending oscillations in the wanted mode by means of atleast one electro-mechanical, especially electro-dynamic, oscillationexciter acting practically directly on the measuring tube and flowedthrough during operation by an electrical current. Furthermore, suchmeasuring transducers comprise a sensor arrangement having oscillationsensors, especially electro-dynamic oscillation sensors, for the atleast pointwise registering of inlet-side and outlet-side oscillationsof the at least one measuring tube, especially those in the Coriolismode, and for producing electrical sensor signals influenced by theprocess parameter to be registered, such as, for instance, the mass flowor the density, and serving as primary signals of the measuringtransducer. As, for example, described in U.S. Pat. No. 7,216,550, inthe case of measuring transducers of the type being discussed, in givencases, also the oscillation exciter can at least at times be used asoscillation sensor and/or an oscillation sensor at least at times can beused as oscillation exciter.

The exciter mechanism of measuring transducers of the type beingdiscussed includes, usually, at least one electrodynamic oscillationexciter and/or an oscillation exciter acting differentially on the atleast one measuring tube and the, in given cases, presentcounteroscillator or the, in given cases, present, other measuring tube,while the sensor arrangement comprises an inlet-side, most oftenlikewise electrodynamic, oscillation sensor as well as at least oneoutlet-side oscillation sensor constructed essentially equally thereto.Such electrodynamic and/or differential oscillation exciters of usuallymarketed measuring transducers of vibration-type are formed by means ofa magnet coil, through which an electrical current flows, at least attimes. In the case of measuring transducers having a measuring tube anda thereto coupled counteroscillator, most often the magnet coil isaffixed to the latter. Such oscillation exciters further include arather elongated, especially rod-shaped, permanent magnet interactingwith the at least one magnet coil, especially plunging into it, andserving as armature and affixed correspondingly to the measuring tube tobe moved. The permanent magnet and the magnet coil serving as excitercoil are, in such case, usually so oriented, that they extendessentially coaxially relative to one another. Additionally, in the caseof conventional measuring transducers, the exciter mechanism is usuallyembodied in such a manner and so placed in the measuring transducer,that it acts essentially centrally on the at least one measuring tube.In such case, the oscillation exciter (and, insofar, the excitermechanism) is, such as, for example, also shown in the case of themeasuring transducers proposed in U.S. Pat. Nos. 5,796,010, 6,840,109,7,077,014 or 7,017,424, most often affixed at least pointwise along animaginary central, peripheral line of the measuring tube outwardlythereon. Alternatively to an exciter mechanism formed by means ofoscillation exciters acting rather centrally and directly on themeasuring tube, as, among other things, provided in U.S. Pat. Nos.6,557,422, 6,092,429 or 4,823,614, for example, also exciter mechanismsformed by means of two oscillation exciters affixed not in the center ofthe measuring tube, but, instead, rather at the inlet and outlet sides,respectively, thereof can be used, or, as, among other things, providedin U.S. Pat. No. 6,223,605 or U.S. Pat. No. 5,531,126, for example, alsoexciter mechanisms formed by means of an oscillation exciter actingbetween the, in given cases, present counteroscillator and the measuringtransducer housing can be used. In the case of most market-usualmeasuring transducers of vibration-type, the oscillation sensors of thesensor arrangement are, as already indicated, at least, insofar as theywork according to the same principle of action, embodied essentially ofequal construction as the at least one oscillation exciter. Accordingly,also the oscillation sensors of such a sensor arrangement are most oftenformed, in each case, by means of at least one magnet coil—usuallyaffixed to the, in given cases, present counteroscillator—, at least attimes passed through by a variable magnetic field and, associatedtherewith, at least at times supplied with an induced measurementvoltage, as well as by means of a permanently magnetic armature, whichdelivers the magnetic field. The armature is affixed to the measuringtube and interacts with the at least one coil. Each of theaforementioned coils is additionally connected by means of at least onepair of electrical connecting lines with the mentioned transmitterelectronics of the in-line measuring device. The connecting lines areled most often on as short as possible paths from the coils via thecounteroscillator to the measuring transducer housing.

As, among other things, discussed in the initially mentioned U.S. Pat.Nos. 7,406,878, 7,305,892, 7,134,348, 6,513,393, 5,861,561, 5,359,881or. WO-A 2004/072588, a further parameter quite relevant for theoperation of the measuring system as such and/or for the operation ofthe plant, in which the measuring system is installed, can be a pressureloss in the flow—, for example, a pressure loss caused by the measuringtransducer and, insofar, by the measuring system. Pressure loss in theflow is important, especially, also for the case, in which the mediumhas two- or more phases, for instance, a liquid gas mixture, and/or inwhich one must contend with, or necessarily prevent, during operation,undesired cavitation as a result a subceeding, or falling beneath, of aminimum static pressure in the flowing medium. In the case of themeasuring systems illustrated in U.S. Pat. No. 5,359,881 or U.S. Pat.No. 7,406,878, a pressure drop across the measuring transducer duringoperation is, for example, ascertained by the features that, at a firstpressure measuring point in the inlet region of the measuringtransducer, or directly upstream therefrom, a first static pressure inthe flowing medium is registered by means of a first pressure sensor,and, at a second pressure measuring point in the outlet region of themeasuring transducer, or directly downstream therefrom, a second staticpressure in the flowing medium is registered by means of an additional,second pressure sensor, and, by means of hydraulic pressure measuringmechanism and/or by means of the respective transmitter electronics,these are repetitively converted into a corresponding pressuredifference, measured value. In U.S. Pat. No. 7,305,892, or U.S. Pat. No.7,134,348, there is additionally described a method executable by meansof a measuring transducer of vibration-type for measuring a pressuredifference, in the case of which, on the basis of an oscillatoryresponse of the at least one measuring tube to a multimodal oscillationexcitation, as well as on the basis of physical-mathematical modelsfurnished in the transmitter electronics for the dynamics of themeasuring system (formed here as a Coriolis, mass flow measuringdevice), a pressure, or pressure drop, in the medium flowing through themeasuring transducer is ascertained.

A disadvantage of the solutions known from the state of the art forpressure measurement, especially also for pressure difference measuringby means of measuring transducer of vibration-type, is, however, to beseen in the fact that either correspondingly modified exciter mechanismsand/or correspondingly modified driver electronics need to be used, or,however, additional pressure sensors provided. Associated therewith,both the design complexity of the measuring system as well as also theexperimental effort in the calibrating of such measuring systemsincrease in extreme measure, since the foundational physicalmathematical models for the pressure-, or the pressure difference,measuring, for the purpose of achieving a high accuracy of measurement,are very complex, and have, associated therewith, a large number ofcoefficients, which need to be supplementally calibrated, in givencases, also in the course of a wet-calibration performed first on-siteat the installed measuring system.

SUMMARY OF THE INVENTION

An object is of the invention, consequently, is to improve measuringsystems formed by means of measuring transducers of vibration-typetoward the goal that, therewith, a measuring of a pressure difference inthe through flowing medium is enabled, which is, at least for purposesof detection, or alarming, of undesirably high pressure drops in theflowing medium, sufficiently exact, and, in given cases, also highlyprecise, in the sense of producing validated, measured values; thisshould be accomplished, especially, also with application of themeasurements technology proven in such measuring systems, such as, forinstance, established oscillation sensors and/or actuation technology,or also proven technologies and architectures of established transmitterelectronics.

For achieving the object, the invention resides in a measuring systemfor a medium, for example, a gas and/or a liquid, a paste or a powder orother flowable material, flowing in a pipeline, which measuring systemcomprises: A measuring transducer of vibration-type, through whichmedium flows during operation and which produces primary signalscorresponding to parameters of the flowing medium, for example, a massflow rate, a density and/or a viscosity; as well as a transmitterelectronics electrically coupled with the measuring transducer foractivating the measuring transducer and for evaluating primary signalsdelivered by the measuring transducer. The measuring transducerincludes: At least one measuring tube for conveying flowing medium; atleast one electro-mechanical, for example, electrodynamic, oscillationexciter for exciting and/or maintaining vibrations of the at least onemeasuring tube, for example, bending oscillations of the at least onemeasuring tube executed about an imaginary oscillation axis imaginarilyconnecting an inlet-side, first measuring tube end of the measuring tubeand an outlet-side, second measuring tube end of the measuring tube andhaving a natural resonance frequency of the measuring transducer; aswell as a, for example, electrodynamic, first oscillation sensor forregistering, for example, inlet-side vibrations of at least the at leastone measuring tube and for producing a first primary signal of themeasuring transducer representing, for example, inlet-side vibrations atleast of the at least one measuring tube. The transmitter electronicsdelivers at least one driver signal for the oscillation exciter foreffecting vibrations, for example, bending oscillations, of the at leastone measuring tube, and generates, by means of the first primary signalas well as with application of a damping, measured value (for example,one held internally in a volatile data memory provided in thetransmitter-electronics and/or produced during operation by means of thedriver signal and/or by means of the first primary signal), whichrepresents an excitation power required for maintaining vibrations ofthe at least one measuring tube, for example, bending oscillations aboutan imaginary oscillation axis imaginarily connecting an inlet-side,first measuring tube end of the measuring tube and an outlet-side,second measuring tube end of the measuring tube and, respectively, adamping (as a result of inner friction in the medium flowing in themeasuring transducer) of vibrations of the at least one measuring tube,for example, bending oscillations about an imaginary oscillation axisimaginarily connecting an inlet-side, first measuring tube end of themeasuring tube and an outlet-side, second measuring tube end of themeasuring tube, a pressure difference, measured value, which representsa pressure difference occurring between two predetermined referencepoints in the flowing medium located, for example, within the measuringtransducer, for example, in such a manner, that a first of the tworeference points is located on the inlet side and a second of the tworeference points is located on the outlet side in the measuringtransducer.

Moreover, the invention resides in a method for measuring a pressuredifference arising within a flowing medium, which method comprises stepsas follows:

-   -   permitting the medium to flow through at least one measuring        tube excited to execute vibrations, especially bending        oscillations about an imaginary oscillation axis imaginarily        connecting an inlet-side, first measuring tube end of the        measuring tube and an outlet-side, second measuring tube end of        the measuring tube;    -   producing a first primary signal, especially one representing        inlet-side, vibrations at least of the at least one measuring        tube;    -   producing an damping, measured value, which represents an        excitation power required for maintaining vibrations of the at        least one measuring tube, for example, bending oscillations        about an imaginary oscillation axis imaginarily connecting an        inlet-side, first measuring tube end of the measuring tube and        an outlet-side, second measuring tube end of the measuring tube,        or a damping of vibrations of the at least one measuring tube,        for example, bending oscillations about an imaginary oscillation        axis imaginarily connecting an inlet-side, first measuring tube        end of the measuring tube and an outlet-side, second measuring        tube end of the measuring tube, as a result of inner friction in        the medium flowing in the measuring transducer; as well as    -   applying the damping, measured value, the first primary signal,        as well as the second primary signal for producing a pressure        difference, measured value, which represents a pressure        difference occurring in the flowing medium between, especially        two reference points located within the measuring transducer.

According to a first embodiment of the measuring system of theinvention, it is additionally provided, that the transmitter electronicsgenerates the damping, measured value by means of the at least onedriver signal, and/or by means of the first primary signal.

According to a second embodiment of the measuring system of theinvention, it is additionally provided, that the transmitterelectronics, for ascertaining the pressure difference, measured value,generates, for example, by means of the first primary signal and/or bymeans of the driver signal and/or by means of the damping, measuredvalue, a viscosity-measured value, which represents a viscosity, η, ofmedium flowing in the measuring transducer.

According to a third embodiment of the measuring system of theinvention, it is additionally provided, that the transmitterelectronics, for ascertaining the pressure difference, measured valueand/or for producing a density, measured value representing a density,ρ, of medium flowing in the measuring transducer on the basis of atleast one of the primary signals and/or on the basis of the at least onedriver signal, generates a frequency, measured value, which representsan oscillation frequency, f_(exc), of vibrations of the at least onemeasuring tube, for example, of bending oscillations of the at least onemeasuring tube executed about an imaginary oscillation axis imaginarilyconnecting an inlet-side, first measuring tube end of the measuring tubeand an outlet-side, second measuring tube end of the measuring tube andhaving a natural resonance frequency of the measuring transducer.

According to a fourth embodiment of the measuring system of theinvention, it is additionally provided, that the transmitter electronicsgenerates the pressure difference, measured value with application of adensity, measured value representing a density, ρ, of medium flowing inthe measuring transducer, especially a density, measured valueinternally held in a volatile data memory of the transmitterelectronics, for example, a density, measured value produced duringoperation by means of the driver signal and/or by means of the firstprimary signal.

According to a fifth embodiment of the measuring system of theinvention, it is additionally provided that the transmitter electronics,for ascertaining the pressure difference, measured value, generates, bymeans of at least one of the primary signals, an amplitude, measuredvalue, which represents an oscillation amplitude, f_(o), of vibrationsof the at least one measuring tube, especially bending oscillationsabout an imaginary oscillation axis imaginarily connecting aninlet-side, first measuring tube end of the measuring tube and anoutlet-side, second measuring tube end of the measuring tube, at anatural resonance frequency of the measuring transducer.

According to a sixth embodiment of the measuring system of theinvention, it is additionally provided that the transmitter electronics,for ascertaining the pressure difference, measured value, generates, forexample, on the basis of the at least one driver signal and/or on thebasis of at least the first primary signal, an exciter, measured value,which represents an exciter force, Fexc, effecting vibrations of the atleast one measuring tube, especially bending oscillations about animaginary oscillation axis imaginarily connecting an inlet-side, firstmeasuring tube end of the measuring tube and an outlet-side, secondmeasuring tube end of the measuring tube, at a natural resonancefrequency of the measuring transducer.

According to a seventh embodiment of the measuring system of theinvention, it is additionally provided that the measuring transducerfurther comprises an, especially electrodynamic, second oscillationsensor for registering vibrations, especially outlet-side vibrations, atleast of the at least one measuring tube and for producing a secondprimary signal of the measuring transducer representing vibrations,especially outlet-side, vibrations, at least of the at least onemeasuring tube. Developing this embodiment of the invention further, itis additionally provided that the transmitter electronics, forascertaining the pressure difference, measured value by means of thefirst primary signal and by means of the second primary signal,generates a phase difference, measured value, which represents a phasedifference, Δ_(φl), existing between the first primary signal and thesecond primary signal, for example, a phase difference, Δ_(φl),dependent on a mass flow rate, {dot over (m)}, of medium flowing in themeasuring transducer and/or that the transmitter electronics, forascertaining the pressure difference, measured value by means of thefirst primary signal and by means of the second primary signal,generates a mass flow, measured value, which represents a mass flowrate, {dot over (m)}, of medium flowing in the measuring transducer,and/or

that the transmitter electronics, for ascertaining the pressuredifference, measured value by means of the first primary signal and bymeans of the second primary signal, generates a flow energy, measuredvalue, which represents a kinetic energy, ρU², of medium flowing in themeasuring transducer dependent on a density, ρ, and a flow velocity, U,of medium flowing in the measuring transducer.

According to an eighth embodiment of the measuring system of theinvention, it is additionally provided that the transmitter electronics,for ascertaining the pressure difference, measured value, generates, forexample, by means of the first primary signal and/or by means of thedriver signal and/or by means of the damping, measured value, a Reynoldsnumber, measured value, which represents a Reynolds number, Re, formedium flowing in the measuring transducer.

According to a ninth embodiment of the measuring system of theinvention, it is additionally provided that the transmitter electronics,for ascertaining the pressure difference, measured value, generates apressure drop coefficient, which represents a pressure drop across themeasuring transducer dependent on the instantaneous Reynolds number, Re,of the flowing medium, for an instantaneous kinetic energy of the mediumflowing in the measuring transducer.

According to a tenth embodiment of the measuring system of theinvention, it is additionally provided, that the transmitterelectronics, with application of the pressure difference, measured valueand on the basis of a first pressure, measured value internally held,especially, in a volatile data memory and representing, especially, afirst pressure reigning in the flowing medium upstream of an outlet endof the measuring transducer and/or downstream of an inlet end of themeasuring transducer, measured, especially, by means of a pressuresensor communicating with the transmitter electronics and/or ascertainedby means of the first and second primary signals of the measuringtransducer and/or a static, first pressure, generates a second pressure,measured value, which represents, especially, a minimum static pressure,p_(crit), within the flowing medium and/or a static, second pressure,p_(crit), classified as critical for the measuring system. Developingthis embodiment of the invention further, it is additionally provided,that the transmitter electronics, with application of the secondpressure, measured value, generates an alarm, which signals, forexample, visually and/or acoustically perceivably, a subceeding, orfalling beneath, of an earlier defined, minimum allowable staticpressure in the medium; and/or that the transmitter electronics, withapplication of the second pressure, measured value, generates an alarm,which signals, for example, visually and/or acoustically perceivably, a,for example, impending, occurrence of cavitation in the medium.

According to a eleventh embodiment of the measuring system of theinvention, such comprises, for producing a pressure, measured valuerepresenting a static pressure reigning in the flowing medium, further apressure sensor serving for registering a static pressure reigning,especially, upstream of an inlet end of the measuring transducer ordownstream of an outlet end of the measuring transducer, in a pipelineconveying the medium, and for communicating with the transmitterelectronics during operation.

According to a twelfth embodiment of the measuring system of theinvention, it is additionally provided, that the transmitterelectronics, with application of the pressure difference, measuredvalue, generates an alarm, which signals, especially, visually and/oracoustically perceivably, an exceeding of an earlier defined, maximumallowable drop of a static pressure in the medium flowing through themeasuring transducer; and/or that the transmitter electronics, withapplication of the pressure difference, measured value, generates analarm, which signals, especially, visually and/or acousticallyperceivably, a too high pressure drop in the medium, as caused by themeasuring transducer.

According to a thirteenth embodiment of the measuring system, themeasuring transducer further includes a measuring transducer housinghaving an inlet-side, first housing end, especially one having aconnecting flange for a line segment supplying medium to the measuringtransducer, and an outlet-side, second housing end, especially onehaving a connecting flange for a line segment removing medium from themeasuring transducer. Developing this embodiment of the inventionfurther, it is additionally provided, that the inlet-side, first housingend of the measuring transducer housing is formed by means of aninlet-side, first flow divider having two, mutually spaced flow openingsand the outlet-side, second housing end of the measuring transducerhousing is formed by means of an outlet-side, second flow divider,having two, mutually spaced flow openings, and that the measuringtransducer has two, mutually parallel measuring tubes for conveyingflowing medium, of which a first measuring tube opens with aninlet-side, first measuring tube end into a first flow opening of thefirst flow divider and with an outlet-side, second measuring tube endinto a first flow opening of the second flow divider, and a secondmeasuring tube opens with an inlet-side, first measuring tube end into asecond flow opening of the first flow divider and with an outlet-side,second measuring tube end into a second flow opening of the second flowdivider; and/or that the pressure difference, measured value representsa pressure difference totally occurring in the flowing medium from thefirst housing end to the second housing end, especially in such a mannerthat the first reference point for the pressure difference representedby the pressure difference, measured value is located in the inlet-side,first housing end of the measuring transducer housing and the secondreference point for the pressure difference represented by the pressuredifference, measured value is located in the outlet-side, second housingend of the measuring transducer housing.

According to a first embodiment of the method of the invention, suchfurther comprises a step for producing, especially with application ofthe first primary signal, a Reynolds number, measured value representinga Reynolds number, Re, for the flowing medium.

According to a second embodiment of the method of the invention, suchfurther comprises a step for producing a second primary signalrepresenting outlet-side vibrations at least of the at least onemeasuring tube. Developing this embodiment of the invention further, itis additionally provided that the method further comprises a step forproducing, by means of the first primary signal and by means of thesecond primary signal, a mass flow, measured value representing a massflow rate of the flowing medium.

According to a third embodiment of the method of the invention, suchfurther comprises a step for producing, by means of the first primarysignal, a density, measured value representing a density of the flowingmedium.

According to a fourth embodiment of the method of the invention, suchfurther comprises a step of using the mass flow, measured value, thedensity, measured value as well as the Reynolds number, measured valuefor producing the pressure difference, measured value.

A basic idea of the invention is to apply a small number of operatingparameters typically internally generated by means of the transmitterelectronics of such measuring systems, such as a phase differencebetween the primary signals representing in- and outlet-sideoscillations of the at least one measuring tube, their signal frequencyand/or -amplitude, and/or measured values established for measuringflowing media and in any event typically derived from such parameters,i.e. measured values such as mass flow rate, density, viscosity and/orReynolds number, which are typically available in any event, especiallyalso are internally ascertained, in measuring systems of the type beingdiscussed, in order to ascertain, as another measured variable ofinterest, a pressure difference. The invention is based, in such case,also on the surprising recognition, that even alone on the basis of theaforementioned operating parameters, or the therefrom derived, inmeasuring systems of the type being discussed typically in any eventascertained, measured values as well as some few earlier specially—, forinstance, in the course of an in any event desired, wet-calibration—tobe determined, measuring system specific constants, pressure differencesin the medium flowing through the measuring transducer can beascertained with an accuracy of measurement sufficiently good also forpurposes of issuing alarms indicating critical operating states, suchas, for instance, cavitation in the flowing medium; this can also beaccomplished over a very broad Reynolds number range, thus both forlaminar as well as also for turbulent flow. An advantage of theinvention is, in such case, especially, that, for implementing thepressure difference measuring of the invention, both operationallyproven, conventional measuring transducers as well as also operationallyproven, conventional transmitter electronics, adapted, of course, asregards the software implemented for the evaluation of the invention,can be used.

The invention as well as other advantageous embodiments thereof will nowbe explained in greater detail on the basis of examples of embodimentspresented in the figures of the drawing. Equal parts are provided in allfigures with equal reference characters; when perspicuity requires or itotherwise appears sensible, already mentioned reference characters areomitted in subsequent figures. Other advantageous embodiments or furtherdevelopments, especially also combinations of first only individuallyexplained aspects of the invention, will become evident additionallyfrom the figures of the drawing, as well as also on the basis of thedependent claims per se.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures of the drawing show as follows:

FIGS. 1 a, b in different side views, a variant of a measuring systemembodied as a compact, measuring device for media flowing in pipelines;

FIGS. 2 a, b in different side views, another variant of a measuringsystem embodied as a compact, measuring device for media flowing inpipelines;

FIG. 3 schematically in the manner of a block diagram, a transmitterelectronics having connected thereto a measuring transducer ofvibration-type, especially a transmitter electronics suitable for ameasuring system according to FIGS. 1 a, 1 b, 2 a, 2 b;

FIGS. 4, 5 in partially sectioned, or perspective, views, a variant of ameasuring transducer of vibration-type, especially a measuringtransducer suitable for a measuring system according to FIGS. 1 a, 1 b;

FIGS. 6, 7 in partially sectioned, or perspective, views, anothervariant of a measuring transducer of vibration-type, especially ameasuring transducer suitable for a measuring system according to FIGS.2 a, 2 b;

FIGS. 8 to 11 results of experimental investigations performed inconnection with the invention, especially results obtained withapplication of computer based simulation programs and/or resultsobtained by means of real measuring systems in the laboratory, orcharacteristic curves derived therefrom, serving for ascertainingpressure difference in a medium flowing through a measuring transducerof vibration-type—, for instance, one according to FIG. 4, 5, or 6, 7;and

FIG. 12 experimentally ascertained pressure loss profiles in aconventional measuring transducer of vibration-type, especially suchobtained with application of computer based simulation programs.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

While the invention is susceptible to various modifications andalternative forms, exemplary embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that there is no intent to limit theinvention to the particular forms disclosed, but on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theintended claims.

FIGS. 1 a, 1 b, or 2 a, 2 b show, in each case, a variant of a measuringsystem suitable for flowable, especially fluid, media and insertable ina process line, for instance, a pipeline of an industrial plant, forexample, a measuring system formed by means of a Coriolis, mass flowmeasuring device, a density measuring device, a viscosity measuringdevice or the like, which serves, especially, for measuring and/ormonitoring a pressure difference of a medium flowing in the processline, on occasion, also, of course, for measuring and/or monitoring atleast one additional physical, measured variable of the medium, such as,for instance, a mass flow rate, a density, a viscosity or the like. Themeasuring system, implemented here by means of an in-line measuringdevice in compact construction, comprises therefor a measuringtransducer MT of vibration-type connected to the process line via aninlet end #111 as well as an outlet end #112, through which measuringtransducer there flows during operation correspondingly the medium to bemeasured, such as, for instance, a low viscosity liquid and/or a highviscosity paste and/or a gas, and which is connected to a transmitterelectronics TE of the measuring system, especially a transmitterelectronics supplied during operation with electrical energy from theexterior via connecting cable and/or internally by means of an energystorer. The transmitter electronics includes, as shown in FIG. 3schematically in the manner of a block diagram, a driver circuit Excserving for activating the measuring transducer MT as well as ameasuring- and evaluating circuit μC of the measuring system forprocessing primary signals of the measuring transducer MT. Themeasuring- and evaluating circuit μC is formed, for example, by means ofa microcomputer and/or communicates during operation with the drivercircuit Exc. During operation, the measuring- and evaluating circuit μCdelivers measured values representing at least one measured variable,such as e.g. instantaneous, or totalled, mass flow. The driver circuitExc and the evaluating circuit μC as well as other electronicscomponents of the transmitter electronics serving the operation of themeasuring system, such as, for instance, internal energy supply circuitsESC for providing internal supply voltages U_(N) and/or communicationcircuits COM serving for connection to a superordinated measurement dataprocessing system and/or to a fieldbus, are additionally accommodated ina corresponding electronics housing 200, especially a housing formedimpact- and/or also explosion resistantly and/or hermetically sealedly.For visualizing measuring system internally produced measured valuesand/or, in given cases, measuring system internally generated statusreports, such as, for instance, an error report or an alarm, on-site,the measuring system can, furthermore, have a display- and operatingelement HMI communicating at least at times with the transmitterelectronics. The display- and operating element can include, forinstance, an LCD-, OLED- or TFT-display placed in the electronicshousing behind a window correspondingly provided therein, as well as acorresponding input keypad and/or a touchscreen. In advantageous manner,the transmitter electronics TE, especially a programmable and/orremotely parameterable, transmitter electronics, can additionally be sodesigned, that it can exchange during operation of the in-line measuringdevice with a thereto superordinated electronic data processing system,for example, a programmable logic controller (PLC), a personal computerand/or a work station, via a data transmission system, for example, afieldbus system and/or wirelessly per radio, measuring- and/or otheroperating data, such as, for instance, current measured values ortuning- and/or diagnostic values serving for control of the in-linemeasuring device. In such case, the transmitter electronics TE can have,for example, an internal energy supply circuit ESC, which is fed duringoperation via the aforementioned fieldbus system by an energy supplyprovided externally in the data processing system. In an embodiment ofthe invention, the transmitter electronics is additionally so embodied,that it is electrically connectable by means of a two-wire-connection 2L, for example, configured as a 4-20 mA-current loop, with the externalelectronic data processing system and can be supplied thereby withelectrical energy. Measured values can, as well, be transmittedthereover to the data processing system. For the case, in which themeasuring system is to be coupled to a fieldbus- or other communicationsystem, the transmitter electronics TE can have a correspondingcommunication interface COM for data communication according to one ofthe relevant industry standards. The electrical connecting of themeasuring transducer to the transmitter electronics can occur by meansof corresponding connecting lines, which are led out from theelectronics housing 200, for example, via cable feed-through, and extendat least sectionally within the measuring transducer housing. Theconnecting lines can, in such case, be embodied, at least partially aselectrical wires, at least sectionally encased in an electricalinsulation, e.g. in the form of “twisted-pair” lines, flat ribbon cablesand/or coaxial cables. Alternatively thereto or in supplementationthereof, the connecting lines can at least sectionally also be formed bymeans of conductive traces of an, especially flexible, in given cases,lacquered, circuit board; compare, for this, also the initiallymentioned U.S. Pat. No. 6,711,958 or U.S. Pat. No. 5,349,872.

FIGS. 4 and 5, or 6 and 7, show schematically, for additionalexplanation of the invention, first, and second examples of embodimentsfor a measuring transducer MT of vibration-type suited for implementingthe measuring system. The measuring transducer MT serves generally forproducing in a through flowing medium, for instance, a gas and/or aliquid, mechanical reaction forces, e.g. mass flow dependent, Coriolisforces, density dependent, inertial forces and/or viscosity dependent,frictional forces, which react measurably, especially registerably bysensor, on the measuring transducer. Derived from these reaction forces,e.g., a mass flow m, a density ρ and/or a viscosity η of the medium canbe measured. Any measuring transducer comprises therefor an inner partarranged in a measuring transducer housing 100 for actually effectingthe physical-electrical transducing of the at least one parameter to bemeasured. Additionally to accommodating the inner part, the measuringtransducer housing 100 can additionally also serve to hold theelectronics housing 200 of the in-line measuring device with thereinaccommodated driver- and evaluating circuits.

For conveying flowing medium, the inner part of the measuring transducercomprises generally at least a first—in the example of an embodimentillustrated in FIGS. 4 and 5, single, at least sectionallycurved—measuring tube 10, which extends with an oscillatory lengthbetween an inlet-side, first measuring tube end 11# and an outlet-side,second measuring tube end 12# and which, for producing theaforementioned reaction forces during operation, is caused to vibrate atleast over its oscillatory length and is, in such case, oscillatingly,repeatedly elastically deformed about a static rest position. Theoscillatory length corresponds, in such case, to a length of animaginary central- or also centroidal, axis extending within the lumenand forming an imaginary connecting line through the centers of gravityof all cross sectional areas of the measuring tube; in the case of acurved measuring tube, thus a stretched length of the measuring tube 10.

It is expressly noted here, that, although the measuring transducer inthe example of an embodiment illustrated in FIGS. 4 and 5 has only asingle, curved measuring tube and at least, insofar, resembles in itsmechanical construction, as well as also in its principle of action thatproposed in U.S. Pat. No. 7,360,451 or U.S. Pat. No. 6,666,098, or alsothat of measuring transducers available from the assignee under the typedesignation “PROMASS H”, “PROMASS P” or “PROMASS S”, of course, alsomeasuring transducers with a straight and/or more than one measuringtube can serve for implementing the invention; compare, for instance,those designs disclosed in the initially mentioned U.S. Pat. Nos.6,006,609, 6,513,393, 7,017,424, 6,840,109, 6,920,798, 5,796,011,5,731,527 or 5,602,345 or, for example, also those measuring transducersavailable from the assignee under the type designation “PROMASS I”,“PROMASS M”, or “PROMASS E” or “PROMASS F”, in each case, having twoparallel measuring tubes. In accordance therewith, the measuringtransducer can also have a single straight, measuring tube or at leasttwo measuring tubes, for example, mechanically coupled with one anotherby means of an inlet-side flow divider and an outlet-side flow divider,in given cases, supplementally also by means of at least one inlet-sidecoupling element and at least one outlet-side coupling element, and/orequally constructed to one another and/or curved and/or parallel to oneanother, for conveying medium to be measured, and vibrating duringoperation, at least at times, for producing the primary signals, forinstance, primary signals of an equal, shared oscillation frequency,however, of mutually opposite phase. In a further development of theinvention, the measuring transducer, such as, for instance,schematically presented in FIGS. 6 and 7, consequently, has,supplementally to the first measuring tube 10, a second measuring tube10′, that is mechanically connected with the first measuring tube 10 forforming a first coupling zone on the inlet side by means of a, forexample, plate-shaped, first coupling element and for forming a secondcoupling zone on the outlet side by means of a, for example,plate-shaped and/or, relative to the first coupling element, equallyconstructed, second coupling element. Also, in this case, thus the firstcoupling zone defines, in each case, an inlet-side, first measuring tubeend 11#, 11′# of each of the two measuring tubes 10, 10′ and the secondcoupling zone, in each case, an outlet-side, second measuring tube end12#, 12′# of each of the two measuring tubes 10, 10′. Since, for thecase, in which the inner part is formed by means of two measuring tubes,each of the two measuring tubes 10, 10′ (especially measuring tubes 10,10′, which, during operation, oscillate with essentially opposite phaserelative to one another and/or are mutually parallel and/or equallyconstructed as regards shape and material) serves for conveying mediumto be measured, each of the two measuring tubes, in an additionalembodiment of this second variant of the measuring transducer of theinvention, opens on the inlet side into, in each case, one of twomutually spaced flow openings of a first flow divider 15 serving fordividing inflowing medium into two flow portions and on the outlet sideinto, in each case, one of two mutually spaced flow openings of a secondflow divider 16 serving for guiding the flow portions back together, sothat thus medium flows simultaneously and in parallel through the twomeasuring tubes during operation of the measuring system. In the exampleof an embodiment illustrated in FIGS. 6 and 7, the flow dividers areintegral components of the measuring transducer housing, wherein thefirst flow divider forms an inlet-side, first housing end defining theinlet end #111 of the measuring transducer and the second flow dividerforms an outlet-side, second housing end defining the outlet end #112 ofthe measuring transducer.

As directly evident from the combination of FIGS. 4 and 5, or 6 and 7,the at least one measuring tube 10 is, in each case, so formed, that theaforementioned center line lies, as quite usual in the case of measuringtransducers of the type being discussed, in an imaginary tube plane ofthe measuring transducer. According to an embodiment of the invention,the at least one measuring tube 10 is, during operation, in such case,so caused to vibrate, that it oscillates, especially in a bendingoscillation mode, about an oscillation axis, which is parallel to orcoincident with an imaginary connecting axis imaginarily connecting thetwo measuring tube ends 11#, 12#. The at least one measuring tube 10 isadditionally so formed and arranged in the measuring transducer, thatthe aforementioned connecting axis extends essentially parallel to, and,in given cases, also coincides with, an imaginary longitudinal axis L ofthe measuring transducers imaginarily connecting the in- and outlet endsof the measuring transducer.

The measuring transducer's at least one measuring tube 10, manufactured,for example, of stainless steel, titanium, tantalum, or zirconium or analloy thereof, and, insofar, also an imaginary center line of themeasuring tube 10 extending within its lumen, can be e.g. essentiallyU-shaped or, as well as also shown in FIGS. 4 and 5, or 6 and 7,essentially V-shaped. Since the measuring transducer should beapplicable for a multitude of most varied applications, especially inthe field of industrial measurements and automation technology, it isadditionally provided, that the measuring tube, depending on applicationof the measuring transducer, has a diameter, which lies in the rangeextending between, for instance, 1 mm and, for instance, 100 mm.

For minimizing disturbing influences acting on an inner part formed bymeans of a single measuring tube, as well as also for reducingoscillatory energy totally released from a measuring transducer to theconnected process line, the inner part of the measuring transducercomprises, according to the example of an embodiment illustrated inFIGS. 4 and 5, furthermore, a counteroscillator 20 mechanically coupledwith the—in this case, single, curved—measuring tube 10 and embodied,for example, similarly as the measuring tube, with U-, or V-shape.Counteroscillator 20 is, as well as also shown in FIG. 2, arrangedlaterally spaced in the measuring transducer from the measuring tube 10and affixed to the measuring tube 10 on the inlet side for forming afirst coupling zone defining the aforementioned first measuring tube end11#—and on the outlet side for forming a second coupling zone definingthe aforementioned second measuring tube end 12#. Counteroscillator20—here a counteroscillator extending essentially parallel to themeasuring tube 10, and, in given cases, also arranged coaxiallythereto—is produced from a metal compatible with the measuring tube asregards thermal expansion, such as, for instance, steel, titanium, orzirconium, and can, in such case, also be, for example, tubular or evenessentially box-shaped. As shown in FIG. 2 or, among other things, alsoprovided in U.S. Pat. No. 7,360,451, counteroscillator 20 can be formed,for example, by means of plates arranged on the left- and right sides ofthe measuring tube 10 or also by blind tubes arranged on the left- andright sides of the measuring tube 10. Alternatively thereto, thecounteroscillator 20 can—as, for instance, provided in U.S. Pat. No.6,666,098—also be formed by means of a single blind tube extendinglaterally of the measuring tube and parallel thereto. As evident from acombination of FIGS. 2 and 3, counteroscillator 20 is, in the example ofan embodiment illustrated here, held to the first measuring tube end 11#by means of at least one inlet-side, first coupler 31 and to the secondmeasuring tube end 12# by means of at least one outlet-side, secondcoupler 32, especially one essentially identical to the coupler 31.Serving as couplers 31, 32 can be, in such case, e.g. simple nodeplates, which are secured in appropriate manner on the inlet side and onthe outlet side, in each case, to measuring tube 10 and tocounteroscillator 20. Additionally,—as provided in the case of theexample of an embodiment illustrated in FIGS. 2 and 3—a completelyclosed box, in each case, formed by means of node plates, mutuallyspaced in the direction of the imaginary longitudinal axis L of themeasuring transducer, together with protruding ends of thecounteroscillator 20 can serve on the inlet side and on the outlet sideas coupler 31, or as coupler 32, as the case may be, or, in given cases,the counteroscillator can also be a partially open framework. Asschematically presented in FIGS. 2 and 3, the measuring tube 10 isadditionally connected via a straight, first connecting tube piece 11opening on the inlet side in the region of the first coupling zone andvia a straight, second connecting tube piece 12 opening on the outletside in the region of the second coupling zone, especially a tube piece12 essentially identical to the first connecting tube piece 11, to aprocess line (not shown) respectively supplying, and draining, themedium, wherein an inlet end of the inlet-side connecting tube piece 11essentially forms the inlet end of the measuring transducer and anoutlet end of the outlet-side connecting tube piece 12 forms the outletend of the measuring transducer. In advantageous manner, the measuringtube 10, including the two connecting tube pieces 11, 12 can beone-piece, so that, for their manufacture, e.g. a single tubular stock,or semifinished part, of a material usual for such measuringtransducers, such as e.g. stainless steel, titanium, zirconium, tantalumor corresponding alloys thereof, can serve. Instead of the measuringtube 10, inlet tube piece 11 and outlet tube piece 12, in each case,being segments of a single, one piece tube, these can, in case required,however, also be produced by means of individual stock, or semifinishedparts, which are subsequently joined together, e.g. welded together. Inthe example of an embodiment illustrated in FIGS. 2 and 3, it isadditionally provided, that the two connecting tube pieces 11, 12, areso oriented relative to one another as well as to an imaginarylongitudinal axis L of the measuring transducer imaginarily connectingthe two coupling zones 11#, 12#, that the inner part formed here bymeans of counteroscillator and measuring tube can, accompanied bytwistings of the two connecting tube pieces 11, 12, move like a pendulumabout the longitudinal axis L. For such purpose, the two connecting tubepieces 11, 12 are so oriented relative to one another, that theessentially straight tube segments extend essentially parallel to theimaginary longitudinal axis L, or to the imaginary oscillation axis ofthe bending oscillations of the measuring tube, such that the tubesegments essentially align both with the longitudinal axis L as well asalso with one another. Since the two connecting tube pieces 11, 12 inthe example of an embodiment illustrated here are essentially straightover their entire length, they are, accordingly, as a whole, orientedessentially aligned with one another as well as with the imaginarylongitudinal axis L. As furthermore evident from FIGS. 2 and 3, themeasuring transducer housing 100 is bending- and torsion-stiffly,especially rigidly, especially in comparison to the measuring tube 10,affixed to an, as regards the first coupling zone, distal inlet end ofthe inlet-side connecting tube piece 11 as well as to an, as regards thefirst coupling zone, distal outlet end of the outlet-side connectingtube piece 12. Insofar, thus the entire inner part—here formed by meansof measuring tube 10 and counteroscillator 20—is not only completelyencased by the measuring transducer housing 100, but, also, as a resultof its eigenmass and the spring action of both connecting tube pieces11, 12, also oscillatably held in the measuring transducer housing 100.

For the typical case, in which the measuring transducer MT is to beassembled releasably with the process line, for example, a process linein the form of a metal pipeline, the measuring transducer has on theinlet side a first connecting flange 13 for connection to a line segmentof the process line supplying medium to the measuring transducer and onthe outlet side a second connecting flange 14 for connection to a linesegment of the process line removing medium from the measuringtransducer. The connecting flanges 13, 14 can, in such case, as quiteusual in the case of measuring transducers of the described type, alsobe integrated terminally into the measuring transducer housing 100. Incase required, the connecting tube pieces 11, 12, can, moreover,however, also be connected directly with the process line, e.g. by meansof welding or hard soldering. In the example of an embodimentillustrated in FIGS. 2 and 3, the first connecting flange 13 is formedon the inlet-side connecting tube piece 11 on its inlet end and thesecond connecting flange 14 on the outlet-side connecting tube piece 12on its outlet end, while, in the example of an embodiment illustrated inFIGS. 4 and 5, the connecting flanges are correspondingly connected withthe associated flow dividers.

For active exciting of mechanical oscillations of the at least onemeasuring tube, or the measuring tubes, as the case may be, especiallyat one or more of its, or their, natural eigenfrequencies, each of themeasuring transducers illustrated in FIGS. 4 to 7 additionally comprisesan electromechanical, especially an electrodynamic (thus formed by meansof a plunging armature, coil pair, or solenoid), exciter mechanism 40.This serves—operated by a correspondingly conditioned, exciter signal,e.g. having a controlled electrical current and/or a controlled voltage,delivered by the driver circuit of the transmitter electronics and, ingiven cases, in the interaction with the measuring- andevaluating-circuit—, in each case, to convert, electrical exciterenergy, or power E_(exc), fed by means of the driver circuit into anexciter force F_(exc) acting, e.g. with pulse shape or harmonically, onthe at least one measuring tube 10 and deflecting such in theabove-described manner. The exciter force F_(exc) can, as usual in thecase of such measuring transducers, be bidirectional or unidirectionaland can be tuned in manner known to those skilled in the art, e.g. bymeans of an electrical current, and/or voltage, control circuit, asregards its amplitude and, e.g. by means of a phase control loop, asregards its frequency. Serving as exciter mechanism 40 can be e.g. anexciter mechanism 40 formed in conventional manner by means of anoscillation exciter 41—, for example, a single electrodynamicoscillation exciter—acting centrally, thus in the region of half of anoscillatory length, on the respective measuring tube. The oscillationexciter 41 can, in the case of an inner part formed by means ofcounteroscillator and measuring tube, as shown in FIG. 4, for example,be formed by means of, secured on the counteroscillator 20, acylindrical exciter coil, through which, during operation, acorresponding exciter current flows and which, associated therewith, ispermeated by a corresponding magnetic field, as well as, at leastpartially plunging into the exciter coil, a permanently magneticarmature, which is affixed externally, especially at half-length, to themeasuring tube 10. Other exciter mechanisms also quite suitable for themeasuring system of the invention for oscillating the at least onemeasuring tube are shown e.g. in the initially mentioned U.S. Pat. Nos.5,705,754, 5,531,126, 6,223,605, 6,666,098 or 7,360,451.

According to an additional embodiment of the invention, the at least onemeasuring tube 10 is actively excited during operation by means of theexciter mechanism, at least at times, in a wanted mode, in which it,especially predominantly or exclusively, executes bending oscillationsabout the mentioned imaginary oscillation axis, for example,predominantly with exactly a natural eigenfrequency (resonancefrequency) of the particular, or the therewith, in each case, formed,inner part of the measuring transducer, such as, for instance, that,which corresponds to a bending oscillation fundamental mode, in whichthe at least one measuring tube has exactly one oscillatory antinode.Especially, in such case, it is additionally provided, that the at leastone measuring tube 10, as quite usual in the case of such measuringtransducers with curved measuring tube, is so excited by means of theexciter mechanism to bending oscillations at an exciter frequencyf_(exc), that it bends out in the wanted mode about the mentionedimaginary oscillation axis—, for instance, in the manner of aunilaterally clamped cantilever—oscillatingly, at least partiallyaccording to one of its natural bending oscillation forms. The bendingoscillations of the measuring tube have, in such case, in the region ofthe inlet-side coupling zone defining the inlet-side measuring tube end11#, an inlet-side oscillation node and, in the region of theoutlet-side coupling zone defining the outlet-side measuring tube end12#, an outlet-side oscillation node, so that thus the measuring tubeextends with its oscillatory length essentially freely oscillatingbetween these two oscillation nodes. In case required, the vibratingmeasuring tube can, however, also, as, for example, provided in U.S.Pat. No. 7,077,014 or JP-A 9-015015, be influenced, with targeting, asregards its oscillatory movements by means of resilient and/orelectromotive, coupling elements acting supplementally correspondinglyin the region of the oscillatory length of the measuring tube. Thedriver circuit can be embodied e.g. as a phase control loop (PLL, orphase locked loop), which is used in manner known to those skilled inthe art to keep an exciter frequency, f_(exc), of the exciter signalcontinually at the instantaneous eigenfrequency of the desired wantedmode. Construction and application of such phase control loops foractive exciting of measuring tubes to oscillations at mechanicaleigenfrequencies is described at length e.g. in U.S. Pat. No. 4,801,897.Of course, also other driver circuits suitable for tuning the exciterenergy, E_(exc), and known, per se, to those skilled in the art can beused, for example, also those mentioned in the initially set-forth stateof the art, for instance, the initially mentioned U.S. Pat. Nos.4,777,833, 4,801,897, 4,879,911, 5,009,109, 5,024,104, 5,050,439,5,804,741, 5,869,770, 6,073495 or 6,311,136. Additionally, as regards anapplication of such driver circuits for measuring transducers ofvibration-type, reference is made to the transmitter electronicsprovided with measurement transmitters of the series “PROMASS 83”, asavailable from the assignee, for example, in connection with measuringtransducers of the series “PROMASS E”, “PROMASS F”, “PROMASS H”,“PROMASS I”, “PROMASS P” or “PROMASS S”. Their driver circuit is, forexample, in each case, so executed, that the lateral bendingoscillations in the wanted mode are controlled to a constant amplitude,thus also largely independent of the density, ρ.

For causing the at least one measuring tube 10 to vibrate, the excitermechanism 40, as already mentioned, is fed by means of a likewiseoscillating exciter signal of adjustable exciter frequency, f_(exc), sothat an exciter current i_(exc) appropriately controlled in itsamplitude flows during operation through the exciter coil of the, here,single oscillation exciter acting on the measuring tube 10, whereby themagnetic field required for moving the measuring tube is produced. Thedriver, or also exciter, signal, or its exciter current i_(exc) can e.g.be harmonically, multifrequently or also rectangularly formed. Theexciter frequency, f_(exc), of the exciter current required formaintaining the bending oscillations of the at least one measuring tube10, in the case of the measuring transducer illustrated in the exampleof an embodiment, can, in advantageous manner, be so selected and set,that the laterally oscillating measuring tube 10 oscillates at leastpredominantly in a bending oscillation, fundamental mode having a singleoscillatory antinade. In accordance therewith, according to anadditional embodiment of the invention, the exciter, or also wantedmode, frequency, f_(exc), is so set, that it corresponds, as exactly aspossible, to an eigenfrequency of bending oscillations of the measuringtube 10, especially that of the bending oscillation, fundamental mode.In the case of application of a measuring tube manufactured of stainlesssteel, especially Hastelloy, having a caliber of 29 mm, a wall thicknesss of, for instance, 1.5 mm, an oscillatory length of, for instance, 420mm and a chordal length, measured between the two measuring tube ends,of 305 mm, the resonance frequency of the same corresponding to thebending oscillation, fundamental mode, for example, in the case of adensity of practically zero, e.g. in the case of a measuring tube filledonly with air, would be, for instance, 490 Hz.

In the example of an embodiment illustrated in FIGS. 4 and 5 having aninner part formed by means of measuring tube and counteroscillator, themeasuring tube 10 executes bending oscillations actively excited bymeans of the exciter mechanism predominantly relative to thecounteroscillator 20, especially at a shared oscillation frequency andmutually opposite phases. In the case of an exciter mechanism actingsimultaneously, for example, differentially, both on the measuring tubeas well as also on the counteroscillator, in such case, also thecounteroscillator 20 is excited simultaneously to cantileveroscillations, and, indeed, such that it oscillates with equal frequency,however, at least partially out of phase, especially with essentiallyopposite phase, to the measuring tube 10 oscillating in the wanted mode.Especially, measuring tube 10 and counteroscillator 20 are, in suchcase, additionally so matched to one another, or so excited, that theyexecute during operation, at least at times and at least partially,bending oscillations opposite-equally, thus with equal-frequency,however, essentially opposite phase, about the longitudinal axis L. Thebending oscillations can, in such case, be so embodied, that they are ofequal modal order and, thus, at least in the case of resting fluid,essentially equally shaped; in the other case of application of twomeasuring tubes, these are, as usual in the case of measuringtransducers of the type being discussed, actively so excited by means ofthe exciter mechanism, especially one acting differentially between thetwo measuring tubes 10, 10′, that they execute during operation, atleast at times, opposite-equal bending oscillations around thelongitudinal axis L. In other words, the two measuring tubes 10, 10′, ormeasuring tube 10 and counteroscillator 20, move then, in each case,relative to one another in the manner of oscillating tuning fork tines.For this case, according to an additional embodiment of the invention,the at least one electro-mechanical, oscillation exciter is designed toexcite, and, respectively, to maintain, opposite-equal vibrations of thefirst measuring tube and the second measuring tube, especially bendingoscillations of each of the measuring tubes, each about an imaginaryoscillation axis imaginarily connecting the relevant first measuringtube end and the relevant second measuring tube end.

For the operationally provided case, in which the medium is flowing inthe process line and, thus, the mass flow m is different from zero, alsoCoriolis forces are induced in the medium by means of the measuring tube10 vibrating in the above described manner. The Coriolis forces, inturn, act on the measuring tube 10 and so effect an additionaldeformation of the same, which is registerable by sensor. Thedeformation occurs essentially according to an additional naturaleigenoscillation form of higher modal order than the wanted mode. Aninstantaneous feature of this so-called Coriolis mode superimposed withequal frequency on the excited wanted mode is, in such case, especiallyas regards amplitude, also dependent on the instantaneous mass flow m.Serving as Coriolis mode, as usual in the case of such measuringtransducers with curved measuring tube, can be e.g. the eigenoscillationform of the anti-symmetric twist mode, thus that, in the case of whichthe measuring tube 10, as already mentioned, also executes rotaryoscillations about an imaginary rotary oscillation axis directedperpendicular to the bending oscillation axis and imaginarilyintersecting the center line of the measuring tube 10 in the region ofhalf the oscillatory length.

For registering oscillations, especially bending oscillations, of the atleast one measuring tube 10, especially also those in the Coriolis mode,the measuring transducer additionally includes, in each case, acorresponding sensor arrangement 50. The sensor arrangement comprises,as also schematically presented in FIGS. 4 to 7, arranged spaced fromthe at least one oscillation exciter on the at least one measuring tube10, for example, an electrodynamic, first oscillation sensor 51, whichdelivers a first primary signal s₁ of the measuring transducerrepresenting vibrations of the measuring tube 10, for example, a voltagecorresponding to the oscillations or an electrical current correspondingto the oscillations, as well as arranged spaced from the firstoscillation sensor 51 on the at least one measuring tube 10, anespecially electrodynamic, second oscillation sensor 52, which deliversa second primary signal s₂ of the measuring transducer representingvibrations of the measuring tube 10. A length of the region of theassociated at least one measuring tube extending between the two, forexample, equally constructed, oscillation sensors, especially anessentially freely oscillatingly vibrating region, corresponds, in suchcase, to a measuring length of the respective measuring transducer. Eachof the—typically broadband—primary signals s₁, s₂ of the measuringtransducer MT has, in such case, in each case, a signal componentcorresponding to the wanted mode and having a signal frequencycorresponding to the instantaneous oscillation frequency, f_(exc), ofthe at least one measuring tube 10 oscillating in the actively excited,wanted mode and a phase shift dependent on the current mass flow of themedium flowing in the at least one measuring tube 10 and measuredrelative to the exciter signal i_(exc), generated, for example, by meansof the PLL-circuit as a function of a phase difference existing betweenat least one of the oscillation measurement signals s₁, s₂ and theexciter current in the exciter mechanism. Even in the case ofapplication of a rather broadband exciter signal i_(exc), as a result ofthe most often very high oscillation quality factor of the measuringtransducer MT, it can be assumed therefrom, that the signal component ofeach of the primary signals corresponding with the wanted modepredominates over other signal components, especially signal componentscorresponding to possible external disturbances and/or classified asnoise, and, insofar, is dominating also at least within a frequencyrange corresponding to a bandwidth of the wanted mode.

In the here illustrated examples of embodiments, in each case, the firstoscillation sensor 51 is arranged on the inlet side and the secondoscillation sensor 52 on the outlet side on the at least one measuringtube 10, especially with the second oscillation sensor 52 being equallywidely spaced from the at least one oscillation exciter, or from thehalf length plane, of the measuring tube 10 as is the first oscillationsensor 51. As quite usual in the case of such measuring transducers ofvibration-type used in measuring systems formed as Coriolis, mass flowmeasuring devices, the first oscillation sensor 51 and the secondoscillation sensor 52 are, according to an embodiment of the invention,additionally arranged in the measuring transducer, in each case, on aside of the measuring tube occupied by the oscillation exciter 41.Furthermore, also the second oscillation sensor 52 can be arranged inthe measuring transducer on the side of the measuring tube occupied bythe first oscillation sensor 51. The oscillation sensors of the sensorarrangement can, in advantageous manner, additionally be so embodied,that they deliver the same type of primary signals, for example, in eachcase, a signal voltage, or a signal current. In an additional embodimentof the invention, both the first oscillation sensor as well as also thesecond oscillation sensor are additionally, in each case, so placed inthe measuring transducer MT, that each of the oscillation sensorsregisters, at least predominantly, vibrations of the at least onemeasuring tube 10. For the above described case, in which the inner partis formed by means of a measuring tube and a counteroscillator coupledtherewith, according to an additional embodiment of the invention, boththe first oscillation sensor as well as also the second oscillationsensor are so embodied and so placed in the measuring transducer, thateach of the oscillation sensors registers, for example, differentially,predominantly oscillations of the measuring tube relative to thecounteroscillator, such that thus both the first primary signal s₁ aswell as also the second primary signal s₂, represent oscillatorymovements, especially opposite-equal, oscillatory movements, of the atleast one measuring tube 10 relative to the counteroscillator 20. Forthe other described case, in which the inner part is formed by means oftwo measuring tubes, especially measuring tubes oscillatingopposite-equally during operation, according to another embodiment ofthe invention, both the first oscillation sensor as well as also thesecond oscillation sensor are so embodied and so placed in the measuringtransducer, that each of the oscillation sensors predominantlyregisters, for example, differentially, oscillations of the firstmeasuring tube 10 relative to the second measuring tube 10′, that thusboth the first primary signal s₁ as well as also the second primarysignal s₂ represent, especially opposite-equally, oscillatory movementsof the two measuring tubes relative to one another, especially in such amanner that—as usual in the case of conventional measuringtransducers—the first primary signal produced by means of the firstoscillation sensor represents inlet-side vibrations of the firstmeasuring tube relative to the second measuring tube and the secondprimary signal produced by means of the second oscillation sensorrepresents outlet-side vibrations of the first measuring tube relativeto the second measuring tube. In an additional embodiment of theinvention, it is additionally provided, that the sensor arrangement hasexactly two oscillation sensors, thus supplementally to the first andsecond oscillation sensors there are no additional oscillation sensors,and, insofar, as regards the used components thus corresponds to aconventional sensor arrangement.

The oscillation measurement signals s₁, s₂, delivered by the sensorarrangement, having, in each case, a signal component signal frequencycorresponding with an instantaneous oscillation frequency, f_(exc), ofthe at least one measuring tube 10 oscillating in the actively excitedwanted mode, are, as also shown in FIG. 3, fed to the transmitterelectronics TE and there then to the therein provided measuring- andevaluating circuit μC. First, they are preprocessed, especiallypreamplified, filtered and digitized, by means of a corresponding inputcircuit IE, in order then to be able to be suitably evaluated. As inputcircuit IE, as well as also as measuring- and evaluating circuit μC,there can be applied, in such case, circuit technologies (for example,also such circuits according to the initially mentioned state of theart) already applied and established in conventional Coriolis, mass flowmeasuring devices for the purpose of converting the primary signals, orof ascertaining mass flow rates and/or totalled mass flows, etc.According to an additional embodiment of the invention, the measuring-and evaluating circuit μC is accordingly also implemented by means of amicrocomputer, for example, a digital signal processor (DSP), providedin the transmitter electronics TE, and by means of program-codecorrespondingly implemented, and running, therein. The program-code canbe stored persistently e.g. in a non-volatile, data memory EEPROM of themicrocomputer and, on the starting of the same, loaded into a volatiledata memory RAM, e.g. integrated in the microcomputer. For suchapplications, suitable processors include e.g. such of type TMS320VC33,as available from the firm, Texas Instruments Inc. Of course, theprimary signals s₁, s₂, are, as already indicated, to be converted intocorresponding digital signals by means of correspondinganalog-to-digital converters A/D of the transmitter electronics TE forprocessing in the microcomputer; compare, for this, for example, theinitially mentioned U.S. Pat. No. 6,311,136 or U.S. Pat. No. 6,073,495or also the aforementioned measurement transmitters of the series“PROMASS 83”.

In the case of the measuring of the invention system, thetransmitter-electronics ME serves, especially, by means of the firstprimary signal and by means of the second primary signal, as well astaking into consideration a damping of vibrations of the at least onemeasuring tube actively excited by means of the exciter mechanism—, forexample, thus of bending oscillations of the at least one measuring tubeabout an imaginary oscillation axis imaginarily connecting aninlet-side, first measuring tube end of the measuring tube and anoutlet-side, second measuring tube end of the measuring tube—as a resultof inner friction in the medium flowing in the measuring transducer, tomeasure a pressure difference, Δp, occurring between two predeterminedreference points in the flowing medium, for example, reference pointslocated within the measuring transducer, such as e.g. a pressure dropbrought about in the flowing medium by the measuring transducer itself.For such purpose, the transmitter electronics ME generates duringoperation, based on the driver signal, especially also based on at leastone of the primary signals, recurringly, a damping, measured valueX_(D), which represents an excitation power required for maintainingvibrations of the at least one measuring tube, especially bendingoscillations about an imaginary oscillation axis imaginarily connectingan inlet-side, first measuring tube end of the measuring tube and anoutlet-side, second measuring tube end of the measuring tube, or adamping of vibrations of the at least one measuring tube, especially ofbending oscillations of the at least one measuring tube about animaginary oscillation axis imaginarily connecting an inlet-side, firstmeasuring tube end of the measuring tube and an outlet-side, secondmeasuring tube end of the measuring tube, as a result of inner frictionin the medium flowing in the measuring transducer. With application ofthe damping, measured value X_(D) as well as the two primary signals,the transmitter electronics ME generates, additionally, a pressuredifference, measured value X_(Δp), which correspondingly represents theaforementioned pressure difference, for example, in such a manner, thata first of the two reference points is located on the inlet side and asecond of the two reference points on the outlet side in the measuringtransducer and, insofar, a pressure difference, Δp_(total), fallingacross the measuring transducer, as a whole, is ascertained.

Suited as information carrier, from which the damping of the vibrationsrequired for generating the pressure difference, measured value can bederived, is, for example, the exciter signal delivered by the drivercircuit of the transmitter electronics, especially an amplitude andfrequency of its electrical current component driving the wanted mode oralso an amplitude of the total, exciter current normalized, in givencases, also to an oscillation amplitude ascertained on the basis of atleast one of the primary signals. Alternatively thereto or insupplementation thereof, however, also an internal control signalserving for tuning the driver signal, or the exciter current, or, forexample, in the case of an exciting of the vibrations of the at leastone measuring tube with an exciter current of fixed, predeterminedamplitude, or amplitude controlled to be constant, also at least one ofthe primary signals, especially an amplitude thereof, can serve asinformation carrier for the damping of interest for ascertaining thepressure difference, measured value. Based thereon, the damping,measured value X_(D) can be ascertained, for example, as, among otherthings, provided in the initially mentioned U.S. Pat. Nos. 5,926,096,7,373,841, US-A 2007/0113678, or WO-A 2007/040468, on the basis of adecay curve of vibrations of the at least one measuring tube, measured,for instance, as an oscillatory response to a pulse-shaped excitioninitiated by means of the exciter mechanism and/or also on the basis ofan oscillation quality factor of vibrations of the at least onemeasuring tube, measured, for example, as an oscillatory response to abroadband excition initiated by means of the exciter mechanism, be itnow, for example, by evaluation of the primary signals in the timedomain or by a spectral analysis of the primary signals. Alternativelythereto or in supplementation thereof, the ascertaining of the damping,measured value X_(D), can occur, as provided, for example, in theinitially mentioned U.S. Pat. No. 6,651,513 or U.S. Pat. No. 7,284,449,very simply also on the basis of the exciter force, F_(exc), (which, asis known, is essentially proportional to the exciter current, i_(exc),driving the exciter mechanism) effecting the vibrations of the at leastone measuring tube—here, thus, the mentioned bending oscillations in thewanted mode—of interest for ascertaining damping; in given cases, alsotaking into consideration an oscillation amplitude, f_(s), for example,a measured or calculated, oscillation amplitude, f_(s), of saidvibrations of the at least one measuring tube. Accordingly, thetransmitter electronics generates, for ascertaining the damping,measured value X_(D) and, insofar, also, according to an additionalembodiment of the invention, for example, on the basis of the at leastone driver signal and/or on the basis of at least one of the primarysignals, an exciter-measured value X_(exc), which represents an exciterforce, F_(exc), effecting vibrations of the at least one measuring tube,especially bending oscillations of the at least one measuring tube aboutan imaginary oscillation axis imaginarily connecting an inlet-side,first measuring tube end of the measuring tube and an outlet-side,second measuring tube end of the measuring tube, with a naturalresonance frequency of the measuring transducer.

Since, for ascertaining the pressure difference, measured value X_(Δp),actually only the damping of the vibrations brought about by the mediumflowing in the measuring transducer is relevant, it can, for increasingthe accuracy of measurement, with which the pressure difference, Δp, islastly ascertained, additionally be quite advantageous, generating thedamping, measured value X_(D), to take into consideration the damping ofvibrations of the at least one measuring tube caused by the measuringtransducer itself. This damping caused alone by the measuring transduceritself—sometimes also referred to as empty tube damping—is, in the caseof conventional measuring transducers of vibration-type, due to theirmost often extremely high oscillation quality factor, usually rathersmall. In consideration of the fact, however, that it can, in verysimple manner, be earlier ascertained as a measuring system parameterand stored as a constant in the transmitter electronics, measuringerrors potentially resulting from the empty tube-damping in theascertaining of the damping, measured value can, without mentionableextra effort, be a priori excluded. Therefore, according to anadditional embodiment of the invention, it is additionally providedthat, in the case of ascertaining the damping, measured value X_(D), orthe exciter, measured value X_(exc), an earlier ascertained, measuringsystem parameter K_(D), which corresponds to a damping of vibrations ofthe at least one measuring tube caused by the measuring transduceritself (empty tube damping), or to an excitation power to be provided onthe part of the exciter mechanism for overcoming empty tube damping, iscorrespondingly taken into consideration, for example, a measuringsystem parameter K_(D) experimentally measured as exciter currenti_(exc,0), in the case of vibrating, empty, measuring tube, or tubes,for example, thus according to the relationship:

X _(exc) =i _(exc,0) −K _(D).  (1)

Furthermore, the accuracy, with which the damping, measured value X_(D)is ascertained and, insofar, also the accuracy of the therefrom derivedpressure difference, measured value X_(Δp), can be further improved bynormalizing the exciter, measured value X_(exc) to an instantaneousoscillation amplitude, for example, that at the site of the vibrationsof the at least one measuring tube registered by the first oscillationsensor or that at the site, at which the exciter force produced by theoscillation exciter is introduced in the at least one measuring tube.Therefore, the transmitter electronics, according to an additionalembodiment of the invention, generates by means of at least one of theprimary signals an amplitudes, measured value X_(S), which represents anoscillation amplitude, f_(s), of vibrations of the at least onemeasuring tube, for example, of bending oscillations of the at least onemeasuring tube, about an imaginary oscillation axis imaginarilyconnecting an inlet-side, first measuring tube end of the measuring tubeand an outlet-side, second measuring tube end of the measuring tube,with a natural resonance frequency of the measuring transducer.Additionally, it is provided, that the transmitter electronicsascertains the damping, measured value X_(D) based on the relationship:

$\begin{matrix}{X_{D} = {\frac{X_{exc}}{X_{s}}.}} & (2)\end{matrix}$

Especially, the transmitter electronics ME is additionally designed toascertain the pressure difference, measured value X_(Δp) also undertaking into consideration both an instantaneous mass flow rate, {dotover (m)}, as well as also an instantaneous density, ρ, as well as athereto corresponding, oscillation frequency, f, of vibrations of the atleast one measuring tube. For such purpose, according to an additionalembodiment of the invention, it is additionally provided, that thetransmitter electronics stores, for example, in the volatile data memoryRAM, a mass flow, measured value X_(m), which represents, as exactly aspossible, the mass flow rate, {dot over (m)}, of the medium conveyedthrough the measuring transducer required for the pressure differencemeasuring, a density-measured value X_(ρ), which represents,instantaneously, a density, ρ, to be measured for the medium, as well asa frequency-measured value X_(f) representing an oscillation frequencyof vibrations, for example, the above mentioned lateral bendingoscillations of the at least one measuring tube 10 in the wanted mode,and that the transmitter electronics ascertains the pressure difference,measured value also under application of the frequency, measured valueX_(f) as well as also the density, measured value X_(p) and the massflow, measured value X_(m). With application of the previously indicatedmeasured values, the pressure difference, measured value X_(Δp), can beascertained, for example, based on the relationship:

$\begin{matrix}{X_{\Delta \; p} = {\left( {K_{{\Delta \; p},1} + {K_{{\Delta \; p},2} \cdot \left\{ \frac{X_{m}}{\begin{matrix}{X_{f} \cdot X_{\rho} \cdot} \\\left\lbrack \sqrt{\begin{matrix}{1 - {K_{{\Delta \; p},5} \cdot}} \\{\frac{1 + {K_{{\Delta \; p},4} \cdot \left( {X_{\rho} - K_{\rho,0}} \right)}}{X_{\rho} \cdot \left( X_{f} \right)^{2}} \cdot X_{D}}\end{matrix}} \right\rbrack^{2}\end{matrix}} \right\}^{K_{{\Delta \; p},3}}}} \right) \cdot \frac{\left( X_{m} \right)^{2}}{X_{\rho}}}} & (3)\end{matrix}$

or based on a corresponding algorithm implemented in the transmitterelectronics, wherein K_(Δp,1), K_(Δp,2), K_(Δp,3), K_(Δp,4), K_(Δp,5),K_(p,0) are earlier experimentally ascertained, especially in the courseof a calibrating the measuring system performed under laboratoryconditions and/or by means of computer based calculations, especiallymeasuring system parameters internally held as constants in anon-volatile data memory. The measuring system parameters can, in suchcase, in advantageous manner, be so selected, that the measuring systemparameter K_(ρ,0) corresponds to a predetermined density, at times, alsoreferred to as reference density, of a reference medium, such as e.g.water, flowing through the measuring transducer, in the case of which,with vibrating measuring tube, no, or only a minimum of, oscillatoryenergy is out-coupled from the measuring transducer.

The transmitter electronics ME, or the therein contained measuring- andevaluating circuit μC, serves, in such case, according to an additionalembodiment of the invention, additionally, to ascertain, recurringly,the mass flow, measured value X_(m) required for ascertaining thepressure difference, measured value X_(Δp) by applying the primarysignals s₁, s₂, delivered by the sensor arrangement 50, for example, onthe basis of a phase difference detected between the primary signals s₁,s₂ generates by the first and second oscillation sensor 51, 52 in thecase of measuring tube 10 oscillating partially in the wanted- andCoriolis modes. For such purpose, the transmitter electronics produces,according to an additional embodiment of the invention, duringoperation, recurringly, a phase difference, measured value X_(Δφ), whichrepresents, instantaneously, the phase difference, Δφ, existing betweenthe first primary signal s₁ and the second primary signal s₂. Thecalculating of the mass flow, measured value X_(m) can, thus, occur,with application of a frequency, measured value X_(f) likewise held inthe transmitter electronics, representing the oscillation frequency ofvibrations, for example, the above mentioned lateral bendingoscillations, of the at least one measuring tube 10 in the wanted mode,for example, based on the known relationship:

$\begin{matrix}{{X_{m} = {K_{m} \cdot \frac{X_{\Delta\varphi}}{X_{f}}}},} & (4)\end{matrix}$

wherein K_(m) is an earlier experimentally ascertained, measuring systemparameter, e.g. ascertained earlier in the course of a calibrating ofthe measuring system and/or by means of computer based calculations,held internally, e.g. in the non-volatile data memory, as a constant,and mediating between the mass flow rate, {dot over (m)}, to be measuredand the quotient formed here between the phase difference, measuredvalue X_(Δφ) and the frequency, measured value X_(f). The frequency,measured value X_(f), in turn, can, in simple manner, e.g. on the basisof the primary signals delivered by the sensor arrangement or also onthe basis of the at least one driver signal supplying the excitermechanism, be ascertained likewise by means of the transmitterelectronics, in manner known to those skilled in the art. Alternatively,or in supplementation, the measuring- and evaluating-circuit of themeasuring system of the invention can additionally also serve togenerate, derived from the oscillation frequency instantaneouslyrepresented by the frequency, measured value X_(f), in manner known, perse, to those skilled in the art, supplementally, also the density,measured value X_(ρ) required for ascertaining the pressure difference,measured value, for example, based on the relationship:

$\begin{matrix}{{X_{\rho} = {K_{\rho,1} + \frac{K_{\rho,2}}{X_{f}^{2}}}},} & (5)\end{matrix}$

wherein K_(ρ,1), K_(ρ,2), are earlier experimentally ascertained,measuring system parameter, for example, ones held internally asconstants in the non-volatile data memory EPROM, which correspondinglymediate between the oscillation frequency represented by the frequency,measured value X_(f) and the density, ρ, to be measured. Additionally,the evaluating circuit can, as quite usual in the case of in-linemeasuring devices of the type being discussed, on occasion, however,also be used to ascertain the viscosity, measured value, X_(η), requiredfor ascertaining the pressure difference, measured value; compare, forthis, also the initially mentioned U.S. Pat. Nos. 7,284,449, 7,017,424,6,910,366, 6,840,109, 5,576,500 or 6,651,513. Suited for ascertainingthe exciter energy or excitation power, or damping, required fordetermining viscosity is, in such case, for example, the exciter signaldelivered by the driver circuit of the transmitter electronics,especially an amplitude and frequency of its electrical currentcomponent driving the wanted mode or also an amplitude of the total,exciter current, in given cases, also normalized to an oscillationamplitude ascertained on the basis of at least one of the primarysignals. Alternatively thereto or in supplementation thereof, however,also an internal control signal serving for tuning the driver signal, orthe exciter current or, for example, in the case of an exciting of thevibrations of the at least one measuring tube with an exciter current offixed, predetermined amplitude, or controlled amplitude to be constant,also at least one of the primary signals, especially an amplitudethereof, can serve as a measure of the exciter energy or excitationpower, or damping, required for ascertaining the viscosity, measuredvalue.

The term contained in the above presented relationship (3), namely theleft side of the relationship

${\frac{\left( X_{m} \right)^{2}}{X_{p}} \sim {\rho \; U^{2}}},$

is essentially proportional to a kinetic energy, ρU², of the mediumflowing in the measuring transducer, such thus depending on the density,ρ, and a flow velocity, U, of the medium flowing in the measuringtransducer. Furthermore, the term likewise contained in saidrelationship (3), namely the left side of the relationship

$\frac{X_{m}}{X_{f} \cdot X_{p} \cdot \left\lbrack \sqrt{1 - {K_{{\Delta \; p},5} \cdot \frac{1 + {K_{{\Delta \; p},4} \cdot \left( {X_{p} - K_{p,0}} \right)}}{X_{p} \cdot \left( X_{f} \right)^{2}} \cdot X_{D}}} \right\rbrack^{2}} \sim {Re}$

is essentially proportional to a Reynolds number, Re, of the mediumflowing in the measuring transducer, or the term likewise containedtherein, namely the left side of the relationship

${X_{f} \cdot X_{p} \cdot \left\lbrack \sqrt{1 - {K_{{\Delta \; p},5} \cdot \frac{1 + {K_{{\Delta \; p},4} \cdot \left( {X_{p} - K_{p,0}} \right)}}{X_{p} \cdot \left( X_{f} \right)^{2}} \cdot X_{D}}} \right\rbrack^{2}} \sim \eta$

is accordingly essentially proportional to the viscosity, η, of themedium flowing in the measuring transducer.

Taking this into consideration, according to another embodiment of theinvention, it is provided that the transmitter electronics ascertainsthe pressure difference, measured value X_(Δp) with application of aninternally held (for instance, in the volatile data memory RAM) flowenergy, measured value X_(Ekin), which represents the kinetic energy,ρU², of the medium flowing in the measuring transducer. In such case,based on the mass flow, measured value X_(m) and the density, measuredvalue X_(ρ), the flow energy, measured value X_(Ekin) can also beascertained directly by means of the transmitter electronics, forinstance, through use of the relationship

$X_{Ekin} = {K_{Ekin} \cdot \frac{\left( X_{m} \right)^{2}}{X_{p}} \cdot}$

Alternatively, or in supplementation, the transmitter electronics canascertain the pressure difference, measured value X_(Δp) by applicationof an internally held (for instance, in the volatile data memory RAM)Reynolds number, measured value X_(re), which represents the Reynoldsnumber, Re, of the medium flowing in the measuring transducer. This canoccur, for example, by application of the mass flow, measured valueX_(m) and an internally held (for instance, in the volatile data memoryRAM), viscosity, measured value X_(η), which represents with therequired accuracy the viscosity, η, required for measuring the pressuredifference, in very simple manner, for instance, based on therelationship

$X_{Re} = {K_{Re} \cdot {\frac{X_{m}}{X_{\eta}}.}}$

The corresponding measuring system parameters K_(Ekin), or K_(Re), areessentially dependent on the effective flow cross section of themeasuring transducer and can be earlier experimentally ascertaineddirectly, e.g., again, in the course of a calibrating of the measuringsystem and/or by means of computer based calculations, and stored in thetransmitter electronics, for example, in the non-volatile data memoryEPROM, as constants specific to the measuring system. Furthermore, thetransmitter electronics can, as quite usual in the case of in-linemeasuring devices of the type being discussed, in given cases, also beused to ascertain the viscosity, measured value X_(η) required forascertaining the pressure difference, measured value; compare, for this,also the initially mentioned U.S. Pat. Nos. 7,284,449, 7,017,424,6,910,366, 6,840,109, 5,576,500 or 6,651,513. With application of thefrequency, measured value, the density, measured value, as well as thedamping, measured value, the viscosity, measured value can beascertained directly in the measuring system, for example, through useof a computing algorithm based on the relationship

${X_{\eta} = {X_{f} \cdot X_{p} \cdot \left\lbrack \sqrt{1 - {K_{{\Delta \; p},5} \cdot \frac{1 + {K_{{\Delta \; p},4} \cdot \left( {X_{p} - K_{p,0}} \right)}}{X_{p} \cdot \left( X_{f} \right)^{2}} \cdot X_{D}}} \right\rbrack^{2}}},$

correspondingly implemented in the transmitter electronics.

The above mentioned function formed by means of the measuring systemparameters K_(Δp,1), K_(Δp,3) and the Reynolds number, measured value(an example of such function ascertained by experimental investigationsis shown in FIG. 9) represents quasi a pressure drop characteristiccurve of the measuring system mediating between the instantaneous, orcurrently valid, Reynolds number Re of the flowing medium and a thereondependent, specific pressure drop for the instantaneous kinetic energy,ρU², of the medium flowing in the measuring transducer. The functionvalues X_(ζ)=K_(Δp,1)+K_(Δp,2)·X_(Re)K_(Δp,3) generated internally inthe transmitter electronics from the pressure drop characteristic curveand referenced subsequently herein as the pressure drop coefficientsX_(ζ), depend only on the instantaneous Reynolds number. The measuringsystem parameters K_(Δp,1), K_(ζΔp,2), K_(Δp,3) defining the pressuredrop, characteristic curve can, for example, be so selected, that afirst of the reference points is located in the inlet end #111 (hereformed by the first housing end of the measuring transducer housing) ofthe measuring transducer, and that a second of the reference points islocated in the outlet end #112 (here formed by the second housing end ofthe measuring transducer housing) of the measuring transducer, so thatthus the pressure difference, measured value X_(Δp), as a result,represents a total pressure difference, Δp_(total), occurring in theflowing medium from the inlet end to the outlet end; compare FIGS. 9 and12. The measuring system parameters and, insofar, the reference pointscan, for example, however, also be so selected, that the pressuredifference, measured value X_(Δp), as shown in FIG. 10, represents amaximal pressure drop, Δp_(max), in the medium flowing within themeasuring transducer. This maximum pressure drop, Δp_(max), arises, asalso evident from the pressure loss profiles illustrated, by way ofexample, in FIG. 12 for measuring transducers of the type beingdiscussed, between the inlet end #111 of the measuring transducer formedby the first housing end and a region of increased turbulence locatedupstream of the outlet end #112 of the measuring transducer formed bythe second housing end. Taking into consideration the pressure drop,characteristic curve, or the pressure drop coefficients X_(ζ), thefunctional relationship proposed for ascertaining the pressuredifference, measured value, can, furthermore, be simplified to therelationship X_(Δp)=X_(ζ)·X_(Ekin). Taking into consideration theaforementioned functional relationships, the pressure difference,measured value X_(Δp) can thus also be ascertained based on one of thefollowing relationships illustrated in FIGS. 9, 10 and 11, respectively,by way of example, on the basis of laboratory measurement data:

${X_{\Delta \; p} = {X_{\zeta} \cdot K_{Ekin} \cdot \frac{\left( X_{m} \right)^{2}}{X_{p}}}},{X_{\Delta \; p} = {\left( {K_{{\Delta \; p},1} + {K_{{\Delta \; p},2} \cdot {X_{Re}}^{{K\;}_{{\Delta \; p},3}}}} \right) \cdot K_{Elkin} \cdot \frac{\left( X_{m} \right)^{2}}{X_{p}}}},{X_{\Delta \; p} = {\left\lbrack {K_{{\Delta \; p},1} + {K_{{\Delta \; p},2} \cdot \left( {K_{Re} \cdot \frac{X_{m}}{X_{\eta}}} \right)^{{K\;}_{{\Delta \; p},3}}}} \right\rbrack \cdot X_{Ekin}}},{or}$$X_{\Delta \; p} = {\left\lbrack {K_{{\Delta \; p},1} + {K_{{\Delta \; p},2} \cdot \left( {K_{Re} \cdot \frac{X_{m}}{X_{\eta}}} \right)^{{K\;}_{{\Delta \; p},3}}}} \right\rbrack \cdot K_{Elkin} \cdot {\frac{\left( X_{m} \right)^{2}}{X_{p}}.}}$

The defined flows of known Reynolds number, Re, known kinetic energy,ρU², and known pressure curve, in each case, required for determiningthe aforementioned measuring system parameters—here, especially, alsomeasuring system parameters required for ascertaining the pressuredifference, measured value—, for example, thus K_(Δp,1), K_(Δp,2),K_(Δp,3), K_(Δp,4), K_(Δp,5), K_(p,0), or K_(Ekin) or K_(Re), can beimplemented directly and sufficiently precisely in correspondingcalibration facilities, for example, by means of calibration media knownas regards flow characteristics, such as e.g. water, glycerin, etc.,which are conveyed by means of correspondingly controlled pumps asimpressed flow on the relevant measuring system to be calibrated.Alternatively thereto or in supplementation thereof, the flowparameters, such as the Reynolds number, the kinetic energy, thepressure difference, etc., required for ascertaining the measuringsystem parameters can, for example, also be ascertained metrologicallyby means of a pressure difference measuring system, which forms,together with the measuring system to be calibrated, one of themeasuring systems proposed in the initially mentioned U.S. Pat. No.7,406,878 and which, for the purpose of a wet calibration, is suppliedwith flows of correspondingly varied mass flow rates, densities andviscosities.

With application of the pressure difference, measured value X_(Δp), itis then possible to correct correspondingly the phase difference betweenthe primary signals s₁, s₂ influenced to a certain degree also by thepressure conditions in the flowing medium or also to correct thelikewise influenced oscillation frequency, for the purpose of increasingthe accuracy of measurement of mass flow- and/or density, measured valueduring operation. Additionally, it is, however, also possible, withapplication of the pressure difference, measured value X_(Δp), tomonitor the measuring system, or a pipeline system connected thereto, asregards states critical for the operation, for instance, the degree of apressure drop in the flowing medium unavoidably caused by the measuringtransducer and/or the therewith associated risk of, most often, damagingcavitation in the flowing medium as a result of a too high pressurereduction.

Therefore, according to an additional embodiment of the invention, thetransmitter electronics is additionally designed to generate, withapplication of the pressure difference, measured value X_(Δp), an alarm,which signals, visually and/or acoustically perceivably, an exceeding ofan earlier defined, maximum allowable drop of static pressure in themedium flowing through the measuring transducer, or a too high pressuredrop in the medium, for example, in the vicinity the measuring system,caused by the measuring transducer. The alarm can be brought about e.g.by the mentioned display- and operating element HMI on-site for displayand/or by a horn controlled by means of the measuring system forhearing.

Alternatively thereto or in supplementation thereof, the transmitterelectronics is, according to an additional embodiment of the invention,designed to generate, on the basis of the pressure difference, measuredvalue as well as an internally held, first pressure, measured valueX_(p1), which represents a first pressure, p_(Ref), reigning in theflowing medium, for example, one impressed by means of a pump providingthe flowing medium and/or set by means of a valve and/or measured bymeans of an additional pressure sensor and/or ascertained by means ofthe transmitter electronics on the basis of at least one of the primarysignals and/or a static, first pressure, p_(Ref), a second pressure,measured value X_(p2), with X_(p2)=X_(p1)−X_(Δp), which represents astatic second pressure, p_(crit), within the flowing medium, forexample, thus a pressure at the site of the outlet-side referencepoint—here thus the second of the two reference points, which define thepressure difference represented by the pressure difference, measuredvalue. For the mentioned case, in which one of the two reference points,by corresponding choice of the measuring system parameters for thepressure drop coefficients, or the pressure drop, characteristic curve,is placed at the earlier exactly ascertained site of minimum pressure(Δp=Δp_(max)) within the medium flowing in the measuring transducer,based on the second pressure, measured value X_(p2), it can then bedetected, for example, during operation of the measuring system,whether, within the measuring transducer or, in given cases, alsodirectly in the outlet region of the connected pipeline lying downstreamof the same, an unallowable low static pressure in the flowing medium isto be reckoned with. Therefore, the transmitter electronics of anadditional embodiment is designed, with application of the secondpressure, measured value X_(p2), in given cases, to generate an alarm,which correspondingly signals, for instance, in a visually and/oracoustically perceivably manner, a subceeding, or falling beneath, of anearlier defined, minimum allowable static pressure in the medium and/oroccurrence, e.g. an impending occurrence, of cavitation in the medium.

The first pressure, measured value X_(p1) can be sent, for example,during operation, from the mentioned superordinated data processingsystem to the transmitter electronics and/or from a pressure sensordirectly connected to the transmitter electronics, and thus, insofar,associated with the measuring system, to the transmitter electronics,and there stored in the mentioned volatile data memory RAM and/or in thenon-volatile data memory EEPROM. Therefore, the measuring system,according to a further development, additionally comprises a pressuresensor communicating during operation with the transmitter electronics,for example, via a direct point-to-point connection and/or wirelesslyper radio, for registering a static pressure reigning, for example,upstream of an inlet end of the measuring transducer or downstream of anoutlet end of the measuring transducer, in a pipeline conveying themedium. Alternatively thereto or in supplementation thereof, thepressure, measured value X_(p1), can, however, also, be ascertained, forexample, with application of pressure measuring methods known to thoseskilled in the art, among other things, from the initially mentionedU.S. Pat. Nos. 6,868,740, 5,734,112, 5,576,500, US-A 2008/0034893 orWO-A 95/29386, WO-A 95/16897, by means of the transmitter electronicsdirectly on the basis of the primary signals. For the case, in which thefirst pressure, measured value X_(p1) represents not exactly thatpressure in the medium, which corresponds to one of the two, referencepoints underpinning the pressure difference, measured value, forinstance, because the pressure sensor delivering the pressure, measuredvalue X_(p1) or the controlled pump delivering the pressure, measuredvalue X_(p1) is farther removed from the inlet end of the measuringtransducer, the pressure, measured value X_(p1), is, of course, to beappropriately converted to the reference point, for instance, bycorresponding subtraction or addition of a known pressure drop arisingbetween the measuring point corresponding to the pressure, measuredvalue X_(p1) and the reference point defined by the calibration of themeasuring system, or is to be correspondingly adjusted to the pressuredrop, characteristic curve underpinning the above mentioned pressuredrop-coefficient by selection of suitable measuring system parameters.

The aforementioned calculational functions, especially also thoseserving, in each case, for producing the pressure difference, measuredvalue X_(Δp), or others of the aforementioned measured values, can beimplemented very simply e.g. by means of the above mentionedmicrocomputer of the evaluating circuit μC or, for example, also adigital signal processor DSP correspondingly provided therein. Thecreation and implementing of corresponding algorithms corresponding tothe above-described formulas or, for example, also simulating theoperation of the mentioned amplitude-, or frequency control circuit forthe exciter mechanism, as well as their translation into program-codecorrespondingly executable in the transmitter electronics, is known, perse, to those skilled in the art and needs, consequently,—in any event,with knowledge of the present invention—no detailed explanation. Ofcourse, the aforementioned formulas, or other functionalities of themeasuring system implemented with the transmitter electronics can alsodirectly, wholly or partially, be implemented by means of correspondingdiscretely constructed and/or hybrid, thus mixed analog-digital,calculational circuits in the transmitter electronics TE.

While the invention has been illustrated and described in detail in thedrawings and forgoing description, such illustration and description isto be considered as exemplary not restrictive in character, it beingunderstood that only exemplary embodiments have been shown and describedand that all changes and modifications that come within the spirit andscope of the invention as described herein are desired to protected.

1. Measuring system, especially compact, measuring device and/orCoriolis, mass flow measuring device for a medium flowing in a pipeline,especially a gas and/or a liquid, a paste or a powder or other flowablematerial, which measuring system comprises: a measuring transducer ofvibration-type, through which, during operation, a medium flows andwhich produces primary signals corresponding with parameters, especiallya mass flow rate, a density and/or a viscosity, of the flowing medium;as well as a transmitter electronics electrically coupled with themeasuring transducer for activating the measuring transducer and forevaluating primary signals delivered by the measuring transducer;wherein the measuring transducer comprises: at least one measuring tubefor conveying flowing medium, at least one electromechanical,oscillation exciter, especially an electrodynamic, oscillation exciter,for exciting and/or maintaining vibrations of the at least one measuringtube; as well as a first oscillation sensor for registering vibrationsat least of the at least one measuring tube and for producing a firstprimary signal of the measuring transducer representing vibrations atleast of the at least one measuring tube; wherein the transmitterelectronics: delivers at least one driver signal for the oscillationexciter effecting vibrations, especially bending oscillations, of the atleast one measuring tube, and, generates, by means of the first primarysignal as well as with application of a damping, measured value (X_(D)),which represents an excitation power required for maintaining vibrationsof the at least one measuring tube and, respectively, a damping as aresult of inner friction in the medium flowing in the measuringtransducer of vibrations of the at least one measuring tube a pressuredifference, measured value (X_(Δp)), which represents a pressuredifference occurring between two predetermined reference points in theflowing medium.
 2. Measuring system as claimed in claim 1, wherein thetransmitter electronics generates the damping, measured value (X_(D)) bymeans of the at least one driver signal; and/or wherein the transmitterelectronics generates the damping, measured value (X_(D)) by means ofthe first primary signal.
 3. Measuring system as claimed in claim 1,wherein the transmitter electronics, for ascertaining the pressuredifference, measured value (X_(Δp)), generates, especially by means ofat least the first primary signal and/or by means of the driver signal,a viscosity, measured value (X_(η)), which represents a viscosity, η, ofmedium flowing in the measuring transducer.
 4. Measuring system asclaimed in claim 3, wherein the transmitter electronics generates theviscosity, measured value (X_(η)) by means of the damping, measuredvalue (X_(D)).
 5. Measuring system as claimed in claim 1, wherein thetransmitter electronics, for ascertaining the pressure difference,measured value (X_(Δp)), generates, on the basis of at least the firstprimary signals and/or on the basis of the at least one driver signal, afrequency, measured value (X_(f)), which represents an oscillationfrequency, f_(exc), of vibrations of the at least one measuring tube,especially bending oscillations of the at least one measuring tube aboutan imaginary oscillation axis imaginarily connecting an inlet-side,first measuring tube end of the measuring tube and an outlet-side,second measuring tube end of the measuring tube, with a naturalresonance frequency of the measuring transducer.
 6. Measuring system asclaimed in claim 1, wherein the transmitter electronics generates thepressure difference, measured value (X_(Δp)) with application of adensity, measured value (X_(ρ)) (especially one held internally in avolatile data memory, especially one produced during operation by meansof the driver signal and/or by means of the first primary signal), whichrepresents a density, ρ, of medium flowing in the measuring transducer.7. Measuring system as claimed in claim 6, wherein the transmitterelectronics generates the density, measured value (X_(ρ)) by means ofthe frequency, measured value (X_(f)), especially based on therelationship: ${X_{p} = {K_{p,1} + \frac{K_{p,2}}{X_{f}^{2}}}},$ whereinK_(ρ,1), K_(ρ,2), are earlier experimentally ascertained measuringsystem parameters, especially ones ascertained in the course of acalibrating of the measuring system and/or produced by means of computerbased calculations, especially ones held as constants internally in anon-volatile data memory provided in the transmitter electronics. 8.Measuring system as claimed in claim 3, wherein the transmitterelectronics generates the viscosity, measured value based on therelationship:$X_{\eta} = {X_{f} \cdot X_{p} \cdot \left\lbrack \sqrt{K_{\eta,1} - {K_{\eta,2} \cdot \frac{1 + {K_{n,3}\left( {{X_{p} - K_{p}},0} \right)}}{X_{p} \cdot \left( X_{f} \right)^{2}} \cdot X_{D}}} \right\rbrack^{2}}$wherein K_(η,1), K_(η,2), K_(η,3), K_(ρ,0) are earlier experimentallyascertained, measuring system parameters, especially ones ascertained inthe course of a calibrating of the measuring system and/or produced bymeans of computer based calculations, especially ones held as constantsinternally in a non-volatile data memory provided in the transmitterelectronics, especially ones ascertained in such a manner that themeasuring system parameter K_(ρ,0) corresponds to a predetermineddensity of a reference medium flowing through the measuring transducer,in the case of which, with vibrating measuring tube, no, or only aminimum of, oscillatory energy is out-coupled from the measuringtransducer.
 9. Measuring system as claimed in claim 1, wherein thetransmitter electronics, for ascertaining the pressure difference,measured value (X_(Δp)), generates, by means of at least one of theprimary signals, an amplitude, measured value (X_(S)), which representsan oscillation amplitude, f_(s), of vibrations of the at least onemeasuring tube, especially bending oscillations of the at least onemeasuring tube about an imaginary oscillation axis imaginarilyconnecting an inlet-side, first measuring tube end of the measuring tubeand an outlet-side, second measuring tube end of the measuring tube,with a natural resonance frequency of the measuring transducer. 10.Measuring system as claimed in claim 1, wherein the transmitterelectronics, for ascertaining the pressure difference, measured value(X_(Δp)), generates, especially on the basis of the at least one driversignal and/or on the basis of at least the first primary signal, anexciter, measured value (X_(exc)), which represents an exciter force,F_(exc), effecting vibrations of the at least one measuring tube,especially bending oscillations of the at least one measuring tube aboutan imaginary oscillation axis imaginarily connecting an inlet-side,first measuring tube end of the measuring tube and an outlet-side,second measuring tube end of the measuring tube, with a naturalresonance frequency of the measuring transducer.
 11. Measuring system asclaimed in claim 9, wherein the transmitter electronics generates thedamping, measured value (X_(D)) based on the relationship:${X_{D} = {\frac{X_{exc}}{X_{s}} + K_{D}}},$ wherein K_(D) is an earlierexperimentally ascertained, measuring system parameter, especially oneascertained in the course of a calibrating of the measuring systemand/or produced by means of computer based calculations, especially oneheld as a constant internally in a non-volatile data memory provided inthe transmitter electronics, especially one ascertained in such a mannerthat it corresponds to damping of vibrations of the at least onemeasuring tube caused by the measuring transducer itself.
 12. Measuringsystem as claimed in claim 1, wherein the measuring transducer furthercomprises a second oscillation sensor, especially an electrodynamic,second oscillation sensor, for registering vibrations, especiallyoutlet-side, vibrations, at least of the at least one measuring tube andfor producing a second primary signal of the measuring transducerrepresenting vibrations, especially outlet-side vibrations, at least ofthe at least one measuring tube.
 13. Measuring system as claimed inclaim 12, wherein the transmitter electronics, for ascertaining thepressure difference, measured value (X_(Δp)), generates, by means of thefirst primary signal and by means of the second primary signal, a phasedifference, measured value (X_(Δφ)), which represents a phasedifference, Δ_(φl), existing between the first primary signal (s₁) andthe second primary signal (s₂), especially a phase difference dependenton a mass flow rate, {dot over (m)}, of medium flowing in the measuringtransducer.
 14. Measuring system as claimed in claim 12, wherein thetransmitter electronics, for ascertaining the pressure difference,measured value (X_(Δp)), generates, by means of the first primary signaland by means of the second primary signal, a mass flow, measured value(X_(m)), which represents a mass flow rate, {dot over (m)}, of mediumflowing in the measuring transducer.
 15. Measuring system as claimed inclaim 14, wherein the transmitter electronics generates a mass flow,measured value (X_(m)) based on the relationship:${X_{m} = {K_{m} \cdot \frac{X_{\Delta \; \phi}}{X_{f}}}},$ whereinK_(m) is an earlier experimentally ascertained, measuring systemparameter, especially one ascertained in the course of a calibrating ofthe measuring system and/or produced by means of computer basedcalculations, especially a measuring system parameter held as a constantinternally in a non-volatile data memory provided in the transmitterelectronics.
 16. Measuring system as claimed in claim 12, wherein thetransmitter electronics, for ascertaining the pressure difference,measured value (X_(Δp)), generates, by means of the first primary signaland by means of the second primary signal, a flow energy, measured value(X_(Ekin)), which represents a kinetic energy, ρU², of medium flowing inthe measuring transducer dependent on a density, ρ, and a flow velocity,U, of medium flowing in the measuring transducer.
 17. Measuring systemas claimed in claim 16, wherein the transmitter electronics generatesthe flow energy, measured value (X_(Ekin)) based on the relationship:${X_{Ekin} = {K_{Ekin} \cdot \frac{\left( X_{m} \right)^{2}}{X_{p}}}},$wherein K_(Ekin) is an earlier experimentally ascertained, measuringsystem parameter, especially one ascertained in the course of acalibrating of the measuring system and/or produced by means of computerbased calculations, especially a measuring system parameter held as aconstant internally in a non-volatile data memory provided in thetransmitter electronics.
 18. Measuring system as claimed in claim 1,wherein the transmitter electronics, for ascertaining the pressuredifference, measured value (X_(Δp)), generates, especially by means ofthe first primary signal and/or by means of the driver signal, aReynolds number, measured value, which represents a Reynolds number, Re,for medium flowing in the measuring transducer.
 19. Measuring system asclaimed in claim 18, wherein the transmitter electronics generates theReynolds number, measured value by means of the damping, measured value(X_(D)).
 20. Measuring system as claimed in claim 1, wherein thetransmitter electronics generates the Reynolds number, measured valuewith application of the viscosity, measured value (X_(η)).
 21. Measuringsystem as claimed in claim 1, wherein the transmitter electronicsgenerates the pressure difference, measured value based on therelationship:${X_{\Delta \; p} = {\left( {K_{\zeta,1} + {K_{\zeta,2} \cdot X_{Re}^{K_{\zeta,3}}}} \right) \cdot K_{Ekin} \cdot \frac{\left( X_{m} \right)^{2}}{X_{p}\;}}},$wherein K_(ζ,1), K_(ζ,2), K_(ζ,3), K_(Ekin) are earlier experimentallyascertained, measuring system parameters, especially ones ascertained inthe course of a calibrating of the measuring system and/or produced bymeans of computer based calculations, especially measuring systemparameters held as constants internally in a non-volatile data memoryprovided in the transmitter electronics.
 22. Measuring system as claimedin claim 1, wherein the transmitter electronics generates the Reynoldsnumber, measured value with application both of the mass flow, measuredvalue (X_(m)) as well as also the viscosity, measured value (X_(η)),especially based on the relationship:${X_{Re} = {K_{Re} \cdot \frac{X_{m}}{X_{\eta}}}},$ wherein K_(Re) is anearlier ascertained, measuring system parameter, especially one held asa constant internally in a non-volatile data memory provided in thetransmitter electronics.
 23. Measuring system as claimed in claim 18,wherein the transmitter electronics, for ascertaining the pressuredifference, measured value (X_(Δp)), generates a pressure dropcoefficient (X_(ζ)), which represents a pressure drop across themeasuring transducer, dependent on the instantaneous Reynolds number,Re, of the flowing medium, referenced to an instantaneous kinetic energyof the medium flowing in the measuring transducer, especially based onthe relationship:X _(ζ) =K _(ζ,1) +K _(ζ,2) ·X _(Re) K _(ζ,3) wherein K_(ζ,1), K_(ζ,2),K_(ζ,3), are earlier experimentally ascertained, measuring systemparameters, especially measuring system parameters held internally asconstants in a non-volatile data memory provided in the transmitterelectronics.
 24. Measuring system as claimed in claim 23, wherein thetransmitter electronics generates the pressure difference, measuredvalue with application of the pressure drop coefficients (X_(ζ)),especially based on the relationship:${X_{\Delta \; p} = {X_{\zeta} \cdot K_{Ekin} \cdot \frac{\left( X_{m} \right)^{2}}{X_{p}\;}}},$wherein K_(Ekin) is an earlier ascertained, measuring system parameter,especially a measuring system parameter held as a constant internally ina non-volatile data memory provided in the transmitter electronics. 25.Measuring system as claimed in claim 1, wherein the transmitterelectronics, with application of the pressure difference, measured valueand on the basis of a first pressure, measured value (X_(p1)), whichrepresents a first pressure, p_(Ref), reigning in the flowing medium,especially a first pressure, measured value (X_(p1)), held internally ina volatile data memory, especially a first pressure, p_(Ref), upstreamof an outlet end of the measuring transducer and/or downstream of aninlet end of the measuring transducer, especially a first pressure,p_(Ref), measured by means of a pressure sensor communicating with thetransmitter electronics and/or ascertained by means of the first andsecond primary signals of the measuring transducer and/or a static, afirst pressure, generates a second pressure, measured value (X_(p2)),which represents a static second pressure, p_(crit), within the flowingmedium, especially a minimum static second pressure, p_(crit), and/or astatic second pressure, p_(crit), classified as critical for themeasuring system.
 26. Measuring system as claimed in claim 25, whereinthe transmitter electronics, with application of the second pressure,measured value (X_(p2)), generates an alarm, which signals, especiallyvisually and/or acoustically perceivably, a subceeding, or fallingbeneath, of an earlier defined, minimum allowable static pressure in themedium; and/or wherein the transmitter electronics, with application ofthe second pressure, measured value (X_(p2)), generates an alarm, whichsignals, especially visually and/or acoustically perceivably, anoccurrence, especially an impending occurrence, of cavitation in themedium.
 27. Measuring system as claimed in claim 1, which, for producinga pressure, measured value (X_(p1)) representing a static pressurereigning in the flowing medium, especially a static pressure upstream ofan inlet end of the measuring transducer or downstream of an outlet endof the measuring transducer, further comprises a pressure sensor servingfor registering a static pressure reigning in a pipeline conveying themedium and for communicating, during operation, with the transmitterelectronics.
 28. Measuring system as claimed in claim 1, wherein thetransmitter electronics, with application of the pressure difference,measured value, generates an alarm, which signals, especially visuallyand/or acoustically perceivably, an exceeding of an earlier defined,maximum allowable drop of a static pressure in the medium flowingthrough the measuring transducer; and/or wherein the transmitterelectronics, with application of the pressure difference, measuredvalue, generates an alarm, which signals, especially visually and/oracoustically perceivably, a too high pressure drop caused by themeasuring transducer in the medium; and/or wherein the reference pointslocated within the measuring transducer.
 29. Measuring system as claimedin claim 1, wherein the measuring transducer further comprises ameasuring transducer housing with an inlet-side, first housing end andwith an outlet-side, second housing end.
 30. Measuring system as claimedin claim 29, wherein the inlet-side, first housing end of the measuringtransducer housing is formed by means of an inlet-side, first flowdivider including two, mutually spaced flow openings and theoutlet-side, second housing end of the measuring transducer housing isformed by means of an outlet-side, second flow divider including two,mutually spaced flow openings, and wherein the measuring transducerincludes two, mutually parallel, measuring tubes for conveying flowingmedium, of which a first measuring tube opens with an inlet-side, firstmeasuring tube end into a first flow opening of the first flow dividerand with an outlet-side, second measuring tube end into a first flowopening of the second flow divider, and a second measuring tube openswith an inlet-side, first measuring tube end into a second flow openingof the first flow divider and with an outlet-side, second measuring tubeend into a second flow opening of the second flow divider.
 31. Measuringsystem as claimed in claim 30, wherein the at least oneelectro-mechanical, oscillation exciter serves for exciting and/ormaintaining opposite equal vibrations of the first measuring tube andthe second measuring tube, especially bending oscillations of each ofthe measuring tubes executed about an imaginary oscillation axisimaginarily connecting the respective first measuring tube end and therespective second measuring tube end at a natural resonance frequency ofthe measuring transducer.
 32. Measuring system as claimed in claim 31,wherein the first primary signal produced by means of the firstoscillation sensor represents inlet-side vibrations of the firstmeasuring tube relative to the second measuring tube and the secondprimary signal produced by means of the second oscillation sensorrepresents outlet-side vibrations of the first measuring tube relativeto the second measuring tube.
 33. Measuring system as claimed in claim29, wherein the pressure difference, measured value (X_(Δp)) representsa totally occurring pressure difference in the flowing medium from thefirst housing end to the second housing end, especially in such a mannerthat the first reference point for the pressure difference representedby the pressure difference, measured value (X_(Δp)) is located in theinlet-side, first housing end of the measuring transducer housing andthe second reference point for the pressure difference represented bythe pressure difference, measured value (X_(Δp)) is located in theoutlet-side, second housing end of the measuring transducer housing. 34.Measuring system as claimed in claim 29, wherein: the inlet-side, firsthousing end includes a connecting flange for a line segment supplyingmedium to the measuring transducer and the outlet-side, second housingend, includes a connecting flange for a line segment removing mediumfrom the measuring transducer.
 35. Measuring system as claimed in claim1, wherein the reference points are located within the measuringtransducer in such a manner, that a first of the two reference points islocated on the inlet side and a second of the two reference points islocated on the outlet side in the measuring transducer.
 36. Method formeasuring a pressure difference arising within a flowing medium, saidmethod comprising: permitting the medium to flow through at least oneexcited measuring tube to execute vibrations, especially bendingoscillations about an imaginary oscillation axis imaginarily connectingan inlet-side, first measuring tube end of the measuring tube and anoutlet-side, second measuring tube end of the measuring tube; producinga first primary signal representing vibrations at least of the at leastone measuring tube; producing a damping, measured value, whichrepresents an excitation power required for maintaining vibrations ofthe at least one measuring tube, and, respectively, a damping ofvibrations of the at least one measuring tube as a result of innerfriction in the medium flowing in the measuring transducer; as well asapplying the damping, measured value, the first primary signal as wellas the second primary signal for producing a pressure difference,measured value, which represents a occurring pressure difference betweentwo reference points in the flowing medium.
 37. Method as claimed inclaim 36, further comprising at least one of: producing, especially withapplication of the first primary signal, a Reynolds number, measuredvalue representing a Reynolds number, Re, for the flowing medium;producing a second primary signal representing outlet-side vibrations atleast of the at least one measuring tube.
 38. Method as claimed in claim37, further comprising: producing a mass flow, measured valuerepresenting a mass flow rate of the flowing medium, especially by meansof the first primary signal and by means of the second primary signal.39. Method as claimed in claim 38, further comprising at least one of:producing, by means of the first primary signal, a density-measuredvalue representing a density of the flowing medium; applying the massflow, measured value, the density, measured value as well as theReynolds number, measured value for the producing the pressuredifference, measured value.